LINUX ADMINISTRATION GUIDE

Shadow Password Suite

2010-01-20T19:50:00.001-08:00

It has all the commands used for managing Linux users and groups. Red Hat Linux uses this suite to provide additional security apart from the encrypted passwords in the /etc/shadow and /etc/gshadow files.

The encrypted password files have more restrictive permissions as compared to /etc/password or /etc/group; and only root user is allowed to view these files, as they are not writable by default.

However these additional efforts from Red-Hat may not do much good unless users select and Administrators allot strong passwords to users. One similar program named “CRACK” can be used to check the strength of the password. A version of it is available as part of the cracklib* RPM package.

Simple passwords based on the dictionary words or simple recognizable pattern such as abcd can be easily decipher with the password-cracking program within minutes. A strong password should comprise upper and lower case letters and numbers, such a password can take upto weeks for some program to decipher. Example

“I ran a mile in 3 minute on Wednesday”

“Irani3moW”- can be your password

Two commands can be used for converting user passwords in the shadow passwords suite:-

1. pwconv:-

It converts a password already existing /etc/passwd and replaces it by “x”; the encrypted username and other information are transferred to the /etc/shadow file.

If new users are added by editing /etc/passwd file, run this command again. This works even if other passwords are already encrypted in /etc/shadow.

2. pwunconv:-

It transfers password back to /etc/passwd and deletes the /etc/shadow file. Be careful using it because it also deletes any password-aging information otherwise saved in /etc/shadow.

Installing Thunderbird E-mail client on Red-hat/CentOS Linux

2009-12-16T07:41:00.000-08:00

Mozilla thunderbird 2 is a full featured email, RSS and newsgroup client which manages your e-mails making it safer, faster and easier than ever before and it is more powerful than ever.

The key features which differentiate “Mozilla Thunderbird” from others are-
Adaptive junk mail controls, saved search folders, global inbox support, message grouping, mail migration from other mail clients, search with filtering tools, tabbed e-mail messages, smart folders, column headings, activity manager, improved address book, gmail integration and much more.

This installation is suitable for all the Linux platforms.

Download the Thunderbird
visit here download Thunderbird

Simply copy the downloaded file to your desktop

Lets first install it as a user "Ankit" under his home directory which is /home/Ankit . open the X terminal and type the following command in it

# cd /home/Ankit/Desktop
# tar -zxvf thunderbird-2.0.0.23.tar.gz
"It will untar the thunderbird download for you and you get output as shown under"-

thunderbird/

thunderbird/removed-files

thunderbird/chrome/

thunderbird/chrome/installed-chrome.txt

thunderbird/chrome/en-US.manifest

thunderbird/chrome/en-US.jar

thunderbird/chrome/toolkit.jar

thunderbird/chrome/comm.manifest

thunderbird/chrome/comm.jar

thunderbird/chrome/toolkit.manifest

thunderbird/chrome/classic.jar

thunderbird/chrome/classic.manifest

thunderbird/chrome/pippki.manifest

thunderbird/chrome/pippki.jar

thunderbird/chrome/messenger.jar

thunderbird/chrome/icons/

thunderbird/chrome/icons/default/

thunderbird/chrome/icons/default/abcardWindow.xpm

thunderbird/chrome/icons/default/addressbookWindow.xpm

thunderbird/chrome/icons/default/messengerWindow.xpm

thunderbird/chrome/icons/default/msgcomposeWindow.xpm

thunderbird/chrome/icons/default/abcardWindow16.xpm

thunderbird/chrome/icons/default/addressbookWindow16.xpm

thunderbird/chrome/icons/default/messengerWindow16.xpm

thunderbird/chrome/icons/default/msgcomposeWindow16.xpm

thunderbird/chrome/icons/default/default.xpm

thunderbird/chrome/US.jar

thunderbird/chrome/newsblog.jar

thunderbird/chrome/messenger.manifest

thunderbird/chrome/newsblog.manifest

thunderbird/components/

thunderbird/components/xpcom_base.xpt

thunderbird/components/xpcom_ds.xpt

thunderbird/components/xpcom_io.xpt

thunderbird/components/xpcom_components.xpt

thunderbird/components/xpcom_threads.xpt

thunderbird/components/xpcom_xpti.xpt

thunderbird/components/proxyObjInst.xpt

thunderbird/components/xpcom_obsolete.xpt

thunderbird/components/xpconnect.xpt

thunderbird/components/unicharutil.xpt

thunderbird/components/uconv.xpt

thunderbird/components/locale.xpt

thunderbird/components/intl.xpt

thunderbird/components/lwbrk.xpt

thunderbird/components/chardet.xpt

thunderbird/components/storage.xpt

thunderbird/components/libjsd.so

thunderbird/components/jsdservice.xpt

thunderbird/components/necko.xpt

thunderbird/components/nsProxyAutoConfig.js

thunderbird/components/necko_cookie.xpt

thunderbird/components/necko_dns.xpt

thunderbird/components/necko_socket.xpt

thunderbird/components/mimetype.xpt

thunderbird/components/necko_strconv.xpt

thunderbird/components/necko_cache.xpt

thunderbird/components/necko_about.xpt

thunderbird/components/necko_data.xpt

thunderbird/components/necko_res.xpt

thunderbird/components/necko_file.xpt

thunderbird/components/necko_http.xpt

thunderbird/components/necko_viewsource.xpt

thunderbird/components/necko_ftp.xpt

thunderbird/components/libjar50.so

thunderbird/components/jar.xpt

thunderbird/components/uriloader.xpt

thunderbird/components/exthandler.xpt

thunderbird/components/prefetch.xpt

thunderbird/components/pref.xpt

thunderbird/components/caps.xpt

thunderbird/components/rdf.xpt

thunderbird/components/saxparser.xpt

thunderbird/components/htmlparser.xpt

thunderbird/components/gfx.xpt

thunderbird/components/imglib2.xpt

thunderbird/components/dom_base.xpt

thunderbird/components/dom_canvas.xpt

thunderbird/components/dom_core.xpt

thunderbird/components/dom_html.xpt

thunderbird/components/dom_events.xpt

thunderbird/components/dom_stylesheets.xpt

thunderbird/components/dom_views.xpt

thunderbird/components/dom_css.xpt

thunderbird/components/dom_sidebar.xpt

thunderbird/components/dom_traversal.xpt

thunderbird/components/dom_range.xpt

thunderbird/components/dom_xbl.xpt

thunderbird/components/dom_xpath.xpt

thunderbird/components/dom_loadsave.xpt

thunderbird/components/dom_xul.xpt

thunderbird/components/dom_storage.xpt

thunderbird/components/dom.xpt

thunderbird/components/widget.xpt

thunderbird/components/content_base.xpt

thunderbird/components/content_html.xpt

thunderbird/components/content_htmldoc.xpt

thunderbird/components/content_xmldoc.xpt

thunderbird/components/xuldoc.xpt

thunderbird/components/xultmpl.xpt

thunderbird/components/content_xslt.xpt

thunderbird/components/content_xtf.xpt

thunderbird/components/layout_base.xpt

thunderbird/components/layout_printing.xpt

thunderbird/components/layout_xul.xpt

thunderbird/components/layout_xul_tree.xpt

thunderbird/components/inspector.xpt

thunderbird/components/shistory.xpt

thunderbird/components/docshell.xpt

thunderbird/components/webshell_idls.xpt

thunderbird/components/embed_base.xpt

thunderbird/components/windowwatcher.xpt

thunderbird/components/find.xpt

thunderbird/components/webbrowserpersist.xpt

thunderbird/components/commandhandler.xpt

thunderbird/components/nsHelperAppDlg.js

thunderbird/components/progressDlg.xpt

thunderbird/components/nsProgressDialog.js

thunderbird/components/jsconsole.xpt

thunderbird/components/webBrowser_core.xpt

thunderbird/components/editor.xpt

thunderbird/components/txtsvc.xpt

thunderbird/components/txmgr.xpt

thunderbird/components/composer.xpt

thunderbird/components/appshell.xpt

thunderbird/components/accessibility-atk.xpt

thunderbird/components/accessibility.xpt

thunderbird/components/chrome.xpt

thunderbird/components/profile.xpt

thunderbird/components/mozbrwsr.xpt

thunderbird/components/mozfind.xpt

thunderbird/components/windowds.xpt

thunderbird/components/filepicker.xpt

thunderbird/components/nsFilePicker.js

thunderbird/components/xpautocomplete.xpt

thunderbird/components/jsconsole-clhandler.js

thunderbird/components/history.xpt

thunderbird/components/bookmarks.xpt

thunderbird/components/toolkitremote.xpt

thunderbird/components/urlformatter.xpt

thunderbird/components/nsURLFormatter.js

thunderbird/components/alerts.xpt

thunderbird/components/fastfind.xpt

thunderbird/components/autocomplete.xpt

thunderbird/components/feeds.xpt

thunderbird/components/FeedProcessor.js

thunderbird/components/downloads.xpt

thunderbird/components/url-classifier.xpt

thunderbird/components/nsUrlClassifierTable.js

thunderbird/components/nsUrlClassifierLib.js

thunderbird/components/nsUrlClassifierListManager.js

thunderbird/components/commandlines.xpt

thunderbird/components/appstartup.xpt

thunderbird/components/nsCloseAllWindows.js

thunderbird/components/nsDefaultCLH.js

thunderbird/components/toolkitprofile.xpt

thunderbird/components/xulapp.xpt

thunderbird/components/extensions.xpt

thunderbird/components/nsExtensionManager.js

thunderbird/components/update.xpt

thunderbird/components/nsUpdateService.js

thunderbird/components/xpinstall.xpt

thunderbird/components/libxpinstall.so

thunderbird/components/pipboot.xpt

thunderbird/components/pipnss.xpt

thunderbird/components/pippki.xpt

thunderbird/components/mozldap.xpt

thunderbird/components/libmozgnome.so

thunderbird/components/mozgnome.xpt

thunderbird/components/mailnews.xpt

thunderbird/components/msgbase.xpt

thunderbird/components/msgsearch.xpt

thunderbird/components/msgdb.xpt

thunderbird/components/msgnews.xpt

thunderbird/components/msglocal.xpt

thunderbird/components/mime.xpt

thunderbird/components/msgcompose.xpt

thunderbird/components/msgimap.xpt

thunderbird/components/addrbook.xpt

thunderbird/components/nsLDAPPrefsService.js

thunderbird/components/nsAbLDAPAttributeMap.js

thunderbird/components/import.xpt

thunderbird/components/impComm4xMail.xpt

thunderbird/components/mdn-service.js

thunderbird/components/mailview.xpt

thunderbird/components/offlineStartup.js

thunderbird/components/msgsmime.xpt

thunderbird/components/smime-service.js

thunderbird/components/wallet.xpt

thunderbird/components/walleteditor.xpt

thunderbird/components/signonviewer.xpt

thunderbird/components/walletpreview.xpt

thunderbird/components/libspellchecker.so

thunderbird/components/spellchecker.xpt

thunderbird/components/libmyspell.so

thunderbird/components/autoconfig.xpt

thunderbird/components/websrvcs.xpt

thunderbird/components/nsInterfaceInfoToIDL.js

thunderbird/components/nsComposerCmdLineHandler.js

thunderbird/components/mailprofilemigration.xpt

thunderbird/components/shellservice.xpt

thunderbird/components/nsSetDefaultMail.js

thunderbird/components/nsMailDefaultHandler.js

thunderbird/components/nsPhishingProtectionApplication.js

thunderbird/components/newsblog.js

thunderbird/defaults/

thunderbird/defaults/autoconfig/

thunderbird/defaults/autoconfig/prefcalls.js

thunderbird/defaults/autoconfig/platform.js

thunderbird/defaults/pref/

thunderbird/defaults/pref/mdn.js

thunderbird/defaults/pref/smime.js

thunderbird/defaults/pref/mailnews.js

thunderbird/defaults/pref/thunderbird-branding.js

thunderbird/defaults/pref/composer.js

thunderbird/defaults/pref/all-l10n.js

thunderbird/defaults/pref/all-thunderbird.js

thunderbird/defaults/pref/channel-prefs.js

thunderbird/defaults/messenger/

thunderbird/defaults/messenger/mailViews.dat

thunderbird/defaults/messenger/US/

thunderbird/defaults/messenger/US/mailViews.dat

thunderbird/defaults/wallet/

thunderbird/defaults/wallet/DistinguishedSchema.tbl

thunderbird/defaults/wallet/FieldSchema.tbl

thunderbird/defaults/wallet/VcardSchema.tbl

thunderbird/defaults/wallet/SchemaConcat.tbl

thunderbird/defaults/wallet/SchemaStrings.tbl

thunderbird/defaults/wallet/PositionalSchema.tbl

thunderbird/defaults/wallet/StateSchema.tbl

thunderbird/defaults/profile/

thunderbird/defaults/profile/mimeTypes.rdf

thunderbird/defaults/profile/localstore.rdf

thunderbird/defaults/profile/US/

thunderbird/defaults/profile/US/mimeTypes.rdf

thunderbird/defaults/profile/US/localstore.rdf

thunderbird/defaults/profile/prefs.js

thunderbird/dependentlibs.list

thunderbird/dictionaries/

thunderbird/dictionaries/en-US.dic

thunderbird/dictionaries/en-US.aff

thunderbird/extensions/

thunderbird/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}/

thunderbird/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}/install.rdf

thunderbird/extensions/talkback@mozilla.org/

thunderbird/extensions/talkback@mozilla.org/chrome.manifest

thunderbird/extensions/talkback@mozilla.org/components/

thunderbird/extensions/talkback@mozilla.org/components/talkback/

thunderbird/extensions/talkback@mozilla.org/components/talkback/XTalkback.ad

thunderbird/extensions/talkback@mozilla.org/components/talkback/talkback.so

thunderbird/extensions/talkback@mozilla.org/components/talkback/master.ini

thunderbird/extensions/talkback@mozilla.org/components/talkback/talkback

thunderbird/extensions/talkback@mozilla.org/components/libqfaservices.so

thunderbird/extensions/talkback@mozilla.org/components/qfaservices.xpt

thunderbird/extensions/talkback@mozilla.org/install.rdf

thunderbird/greprefs/

thunderbird/greprefs/security-prefs.js

thunderbird/greprefs/all.js

thunderbird/greprefs/xpinstall.js

thunderbird/icons/

thunderbird/icons/mozicon50.xpm

thunderbird/icons/mozicon16.xpm

thunderbird/init.d/

thunderbird/init.d/README

thunderbird/isp/

thunderbird/isp/SpamAssassin.sfd

thunderbird/isp/SpamPal.sfd

thunderbird/isp/movemail.rdf

thunderbird/isp/en-US/

thunderbird/isp/en-US/gmail.rdf

thunderbird/isp/rss.rdf

thunderbird/libfreebl3.chk

thunderbird/libfreebl3.so

thunderbird/libldap50.so

thunderbird/libmozjs.so

thunderbird/libnspr4.so

thunderbird/libnss3.so

thunderbird/libnssckbi.so

thunderbird/libnssdbm3.so

thunderbird/libnssutil3.so

thunderbird/libplc4.so

thunderbird/libplds4.so

thunderbird/libprldap50.so

thunderbird/libsmime3.so

thunderbird/libsoftokn3.chk

thunderbird/libsoftokn3.so

thunderbird/libsqlite3.so

thunderbird/libssl3.so

thunderbird/libxpcom_compat.so

thunderbird/libxpcom_core.so

thunderbird/libxpcom.so

thunderbird/libxpistub.so

thunderbird/license.html

thunderbird/LICENSE.txt

thunderbird/mozilla-installer-bin

thunderbird/mozilla-xremote-client

thunderbird/README.txt

thunderbird/res/

thunderbird/res/entityTables/

thunderbird/res/entityTables/htmlEntityVersions.properties

thunderbird/res/entityTables/html40Latin1.properties

thunderbird/res/entityTables/html40Symbols.properties

thunderbird/res/entityTables/html40Special.properties

thunderbird/res/entityTables/transliterate.properties

thunderbird/res/charsetalias.properties

thunderbird/res/charsetData.properties

thunderbird/res/unixcharset.properties

thunderbird/res/langGroups.properties

thunderbird/res/language.properties

thunderbird/res/sample.unixpsfonts.properties

thunderbird/res/fonts/

thunderbird/res/fonts/fontEncoding.properties

thunderbird/res/fonts/pangoFontEncoding.properties

thunderbird/res/hiddenWindow.html

thunderbird/res/dtd/

thunderbird/res/dtd/xhtml11.dtd

thunderbird/res/forms.css

thunderbird/res/ua.css

thunderbird/res/html.css

thunderbird/res/quirk.css

thunderbird/res/broken-image.gif

thunderbird/res/EditorOverride.css

thunderbird/res/grabber.gif

thunderbird/res/table-add-column-after-active.gif

thunderbird/res/table-add-column-after-hover.gif

thunderbird/res/table-add-column-after.gif

thunderbird/res/table-add-column-before-active.gif

thunderbird/res/table-add-column-before-hover.gif

thunderbird/res/table-add-column-before.gif

thunderbird/res/table-add-row-after-active.gif

thunderbird/res/table-add-row-after-hover.gif

thunderbird/res/table-add-row-after.gif

thunderbird/res/table-add-row-before-active.gif

thunderbird/res/table-add-row-before-hover.gif

thunderbird/res/table-add-row-before.gif

thunderbird/res/table-remove-column-active.gif

thunderbird/res/table-remove-column-hover.gif

thunderbird/res/table-remove-column.gif

thunderbird/res/table-remove-row-active.gif

thunderbird/res/table-remove-row-hover.gif

thunderbird/res/table-remove-row.gif

thunderbird/run-mozilla.sh

thunderbird/thunderbird

thunderbird/thunderbird-bin

thunderbird/updater

thunderbird/updater.ini

thunderbird/updates/

thunderbird/updates/0/

thunderbird/xpicleanup

thats itYour software is successfully installed now. To start the thunderbird mail client, enter:

#cd thunderbird

# ./thunderbird

Now you are ready to use it. But if you like to install it for everyone loging on to Linux server you can do it with the root user account.
You will need to install the thunderbird in /opt directory. Login as root user

#cd /opt
#mkdir thunderbird
#cd thunderbird
#cp /home/Ankit/Desktop/Thunderbird-2.0.0.23.tar.gz /opt/thunderbird

#tar -zxvf Thunderbird-2.0.0.23.tar.gz

thunderbird/
thunderbird/removed-files
thunderbird/chrome/
thunderbird/chrome/installed-chrome.txt
thunderbird/chrome/en-US.manifest
thunderbird/chrome/en-US.jar
thunderbird/chrome/toolkit.jar
thunderbird/chrome/comm.manifest
thunderbird/chrome/comm.jar
thunderbird/chrome/toolkit.manifest
thunderbird/chrome/classic.jar
thunderbird/chrome/classic.manifest
thunderbird/chrome/pippki.manifest
thunderbird/chrome/pippki.jar
thunderbird/chrome/messenger.jar
thunderbird/chrome/icons/
thunderbird/chrome/icons/default/
thunderbird/chrome/icons/default/abcardWindow.xpm
thunderbird/chrome/icons/default/addressbookWindow.xpm
thunderbird/chrome/icons/default/messengerWindow.xpm
thunderbird/chrome/icons/default/msgcomposeWindow.xpm
thunderbird/chrome/icons/default/abcardWindow16.xpm
thunderbird/chrome/icons/default/addressbookWindow16.xpm
thunderbird/chrome/icons/default/messengerWindow16.xpm
thunderbird/chrome/icons/default/msgcomposeWindow16.xpm
thunderbird/chrome/icons/default/default.xpm
thunderbird/chrome/US.jar
thunderbird/chrome/newsblog.jar
thunderbird/chrome/messenger.manifest
thunderbird/chrome/newsblog.manifest
thunderbird/components/
thunderbird/components/xpcom_base.xpt
thunderbird/components/xpcom_ds.xpt
thunderbird/components/xpcom_io.xpt
thunderbird/components/xpcom_components.xpt
thunderbird/components/xpcom_threads.xpt
thunderbird/components/xpcom_xpti.xpt
thunderbird/components/proxyObjInst.xpt
thunderbird/components/xpcom_obsolete.xpt
thunderbird/components/xpconnect.xpt
thunderbird/components/unicharutil.xpt
thunderbird/components/uconv.xpt
thunderbird/components/locale.xpt
thunderbird/components/intl.xpt
thunderbird/components/lwbrk.xpt
thunderbird/components/chardet.xpt
thunderbird/components/storage.xpt
thunderbird/components/libjsd.so
thunderbird/components/jsdservice.xpt
thunderbird/components/necko.xpt
thunderbird/components/nsProxyAutoConfig.js
thunderbird/components/necko_cookie.xpt
thunderbird/components/necko_dns.xpt
thunderbird/components/necko_socket.xpt
thunderbird/components/mimetype.xpt
thunderbird/components/necko_strconv.xpt
thunderbird/components/necko_cache.xpt
thunderbird/components/necko_about.xpt
thunderbird/components/necko_data.xpt
thunderbird/components/necko_res.xpt
thunderbird/components/necko_file.xpt
thunderbird/components/necko_http.xpt
thunderbird/components/necko_viewsource.xpt
thunderbird/components/necko_ftp.xpt
thunderbird/components/libjar50.so
thunderbird/components/jar.xpt
thunderbird/components/uriloader.xpt
thunderbird/components/exthandler.xpt
thunderbird/components/prefetch.xpt
thunderbird/components/pref.xpt
thunderbird/components/caps.xpt
thunderbird/components/rdf.xpt
thunderbird/components/saxparser.xpt
thunderbird/components/htmlparser.xpt
thunderbird/components/gfx.xpt
thunderbird/components/imglib2.xpt
thunderbird/components/dom_base.xpt
thunderbird/components/dom_canvas.xpt
thunderbird/components/dom_core.xpt
thunderbird/components/dom_html.xpt
thunderbird/components/dom_events.xpt
thunderbird/components/dom_stylesheets.xpt
thunderbird/components/dom_views.xpt
thunderbird/components/dom_css.xpt
thunderbird/components/dom_sidebar.xpt
thunderbird/components/dom_traversal.xpt
thunderbird/components/dom_range.xpt
thunderbird/components/dom_xbl.xpt
thunderbird/components/dom_xpath.xpt
thunderbird/components/dom_loadsave.xpt
thunderbird/components/dom_xul.xpt
thunderbird/components/dom_storage.xpt
thunderbird/components/dom.xpt
thunderbird/components/widget.xpt
thunderbird/components/content_base.xpt
thunderbird/components/content_html.xpt
thunderbird/components/content_htmldoc.xpt
thunderbird/components/content_xmldoc.xpt
thunderbird/components/xuldoc.xpt
thunderbird/components/xultmpl.xpt
thunderbird/components/content_xslt.xpt
thunderbird/components/content_xtf.xpt
thunderbird/components/layout_base.xpt
thunderbird/components/layout_printing.xpt
thunderbird/components/layout_xul.xpt
thunderbird/components/layout_xul_tree.xpt
thunderbird/components/inspector.xpt
thunderbird/components/shistory.xpt
thunderbird/components/docshell.xpt
thunderbird/components/webshell_idls.xpt
thunderbird/components/embed_base.xpt
thunderbird/components/windowwatcher.xpt
thunderbird/components/find.xpt
thunderbird/components/webbrowserpersist.xpt
thunderbird/components/commandhandler.xpt
thunderbird/components/nsHelperAppDlg.js
thunderbird/components/progressDlg.xpt
thunderbird/components/nsProgressDialog.js
thunderbird/components/jsconsole.xpt
thunderbird/components/webBrowser_core.xpt
thunderbird/components/editor.xpt
thunderbird/components/txtsvc.xpt
thunderbird/components/txmgr.xpt
thunderbird/components/composer.xpt
thunderbird/components/appshell.xpt
thunderbird/components/accessibility-atk.xpt
thunderbird/components/accessibility.xpt
thunderbird/components/chrome.xpt
thunderbird/components/profile.xpt
thunderbird/components/mozbrwsr.xpt
thunderbird/components/mozfind.xpt
thunderbird/components/windowds.xpt
thunderbird/components/filepicker.xpt
thunderbird/components/nsFilePicker.js
thunderbird/components/xpautocomplete.xpt
thunderbird/components/jsconsole-clhandler.js
thunderbird/components/history.xpt
thunderbird/components/bookmarks.xpt
thunderbird/components/toolkitremote.xpt
thunderbird/components/urlformatter.xpt
thunderbird/components/nsURLFormatter.js
thunderbird/components/alerts.xpt
thunderbird/components/fastfind.xpt
thunderbird/components/autocomplete.xpt
thunderbird/components/feeds.xpt
thunderbird/components/FeedProcessor.js
thunderbird/components/downloads.xpt
thunderbird/components/url-classifier.xpt
thunderbird/components/nsUrlClassifierTable.js
thunderbird/components/nsUrlClassifierLib.js
thunderbird/components/nsUrlClassifierListManager.js
thunderbird/components/commandlines.xpt
thunderbird/components/appstartup.xpt
thunderbird/components/nsCloseAllWindows.js
thunderbird/components/nsDefaultCLH.js
thunderbird/components/toolkitprofile.xpt
thunderbird/components/xulapp.xpt
thunderbird/components/extensions.xpt
thunderbird/components/nsExtensionManager.js
thunderbird/components/update.xpt
thunderbird/components/nsUpdateService.js
thunderbird/components/xpinstall.xpt
thunderbird/components/libxpinstall.so
thunderbird/components/pipboot.xpt
thunderbird/components/pipnss.xpt
thunderbird/components/pippki.xpt
thunderbird/components/mozldap.xpt
thunderbird/components/libmozgnome.so
thunderbird/components/mozgnome.xpt
thunderbird/components/mailnews.xpt
thunderbird/components/msgbase.xpt
thunderbird/components/msgsearch.xpt
thunderbird/components/msgdb.xpt
thunderbird/components/msgnews.xpt
thunderbird/components/msglocal.xpt
thunderbird/components/mime.xpt
thunderbird/components/msgcompose.xpt
thunderbird/components/msgimap.xpt
thunderbird/components/addrbook.xpt
thunderbird/components/nsLDAPPrefsService.js
thunderbird/components/nsAbLDAPAttributeMap.js
thunderbird/components/import.xpt
thunderbird/components/impComm4xMail.xpt
thunderbird/components/mdn-service.js
thunderbird/components/mailview.xpt
thunderbird/components/offlineStartup.js
thunderbird/components/msgsmime.xpt
thunderbird/components/smime-service.js
thunderbird/components/wallet.xpt
thunderbird/components/walleteditor.xpt
thunderbird/components/signonviewer.xpt
thunderbird/components/walletpreview.xpt
thunderbird/components/libspellchecker.so
thunderbird/components/spellchecker.xpt
thunderbird/components/libmyspell.so
thunderbird/components/autoconfig.xpt
thunderbird/components/websrvcs.xpt
thunderbird/components/nsInterfaceInfoToIDL.js
thunderbird/components/nsComposerCmdLineHandler.js
thunderbird/components/mailprofilemigration.xpt
thunderbird/components/shellservice.xpt
thunderbird/components/nsSetDefaultMail.js
thunderbird/components/nsMailDefaultHandler.js
thunderbird/components/nsPhishingProtectionApplication.js
thunderbird/components/newsblog.js
thunderbird/defaults/
thunderbird/defaults/autoconfig/
thunderbird/defaults/autoconfig/prefcalls.js
thunderbird/defaults/autoconfig/platform.js
thunderbird/defaults/pref/
thunderbird/defaults/pref/mdn.js
thunderbird/defaults/pref/smime.js
thunderbird/defaults/pref/mailnews.js
thunderbird/defaults/pref/thunderbird-branding.js
thunderbird/defaults/pref/composer.js
thunderbird/defaults/pref/all-l10n.js
thunderbird/defaults/pref/all-thunderbird.js
thunderbird/defaults/pref/channel-prefs.js
thunderbird/defaults/messenger/
thunderbird/defaults/messenger/mailViews.dat
thunderbird/defaults/messenger/US/
thunderbird/defaults/messenger/US/mailViews.dat
thunderbird/defaults/wallet/
thunderbird/defaults/wallet/DistinguishedSchema.tbl
thunderbird/defaults/wallet/FieldSchema.tbl
thunderbird/defaults/wallet/VcardSchema.tbl
thunderbird/defaults/wallet/SchemaConcat.tbl
thunderbird/defaults/wallet/SchemaStrings.tbl
thunderbird/defaults/wallet/PositionalSchema.tbl
thunderbird/defaults/wallet/StateSchema.tbl
thunderbird/defaults/profile/
thunderbird/defaults/profile/mimeTypes.rdf
thunderbird/defaults/profile/localstore.rdf
thunderbird/defaults/profile/US/
thunderbird/defaults/profile/US/mimeTypes.rdf
thunderbird/defaults/profile/US/localstore.rdf
thunderbird/defaults/profile/prefs.js
thunderbird/dependentlibs.list
thunderbird/dictionaries/
thunderbird/dictionaries/en-US.dic
thunderbird/dictionaries/en-US.aff
thunderbird/extensions/
thunderbird/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}/
thunderbird/extensions/{972ce4c6-7e08-4474-a285-3208198ce6fd}/install.rdf
thunderbird/extensions/talkback@mozilla.org/
thunderbird/extensions/talkback@mozilla.org/chrome.manifest
thunderbird/extensions/talkback@mozilla.org/components/
thunderbird/extensions/talkback@mozilla.org/components/talkback/
thunderbird/extensions/talkback@mozilla.org/components/talkback/XTalkback.ad
thunderbird/extensions/talkback@mozilla.org/components/talkback/talkback.so
thunderbird/extensions/talkback@mozilla.org/components/talkback/master.ini
thunderbird/extensions/talkback@mozilla.org/components/talkback/talkback
thunderbird/extensions/talkback@mozilla.org/components/libqfaservices.so
thunderbird/extensions/talkback@mozilla.org/components/qfaservices.xpt
thunderbird/extensions/talkback@mozilla.org/install.rdf
thunderbird/greprefs/
thunderbird/greprefs/security-prefs.js
thunderbird/greprefs/all.js
thunderbird/greprefs/xpinstall.js
thunderbird/icons/
thunderbird/icons/mozicon50.xpm
thunderbird/icons/mozicon16.xpm
thunderbird/init.d/
thunderbird/init.d/README
thunderbird/isp/
thunderbird/isp/SpamAssassin.sfd
thunderbird/isp/SpamPal.sfd
thunderbird/isp/movemail.rdf
thunderbird/isp/en-US/
thunderbird/isp/en-US/gmail.rdf
thunderbird/isp/rss.rdf
thunderbird/libfreebl3.chk
thunderbird/libfreebl3.so
thunderbird/libldap50.so
thunderbird/libmozjs.so
thunderbird/libnspr4.so
thunderbird/libnss3.so
thunderbird/libnssckbi.so
thunderbird/libnssdbm3.so
thunderbird/libnssutil3.so
thunderbird/libplc4.so
thunderbird/libplds4.so
thunderbird/libprldap50.so
thunderbird/libsmime3.so
thunderbird/libsoftokn3.chk
thunderbird/libsoftokn3.so
thunderbird/libsqlite3.so
thunderbird/libssl3.so
thunderbird/libxpcom_compat.so
thunderbird/libxpcom_core.so
thunderbird/libxpcom.so
thunderbird/libxpistub.so
thunderbird/license.html
thunderbird/LICENSE.txt
thunderbird/mozilla-installer-bin
thunderbird/mozilla-xremote-client
thunderbird/README.txt
thunderbird/res/
thunderbird/res/entityTables/
thunderbird/res/entityTables/htmlEntityVersions.properties
thunderbird/res/entityTables/html40Latin1.properties
thunderbird/res/entityTables/html40Symbols.properties
thunderbird/res/entityTables/html40Special.properties
thunderbird/res/entityTables/transliterate.properties
thunderbird/res/charsetalias.properties
thunderbird/res/charsetData.properties
thunderbird/res/unixcharset.properties
thunderbird/res/langGroups.properties
thunderbird/res/language.properties
thunderbird/res/sample.unixpsfonts.properties
thunderbird/res/fonts/
thunderbird/res/fonts/fontEncoding.properties
thunderbird/res/fonts/pangoFontEncoding.properties
thunderbird/res/hiddenWindow.html
thunderbird/res/dtd/
thunderbird/res/dtd/xhtml11.dtd
thunderbird/res/forms.css
thunderbird/res/ua.css
thunderbird/res/html.css
thunderbird/res/quirk.css
thunderbird/res/broken-image.gif
thunderbird/res/EditorOverride.css
thunderbird/res/grabber.gif
thunderbird/res/table-add-column-after-active.gif
thunderbird/res/table-add-column-after-hover.gif
thunderbird/res/table-add-column-after.gif
thunderbird/res/table-add-column-before-active.gif
thunderbird/res/table-add-column-before-hover.gif
thunderbird/res/table-add-column-before.gif
thunderbird/res/table-add-row-after-active.gif
thunderbird/res/table-add-row-after-hover.gif
thunderbird/res/table-add-row-after.gif
thunderbird/res/table-add-row-before-active.gif
thunderbird/res/table-add-row-before-hover.gif
thunderbird/res/table-add-row-before.gif
thunderbird/res/table-remove-column-active.gif
thunderbird/res/table-remove-column-hover.gif
thunderbird/res/table-remove-column.gif
thunderbird/res/table-remove-row-active.gif
thunderbird/res/table-remove-row-hover.gif
thunderbird/res/table-remove-row.gif
thunderbird/run-mozilla.sh
thunderbird/thunderbird
thunderbird/thunderbird-bin
thunderbird/updater
thunderbird/updater.ini
thunderbird/updates/
thunderbird/updates/0/
thunderbird/xpicleanup

Now to start the thunderbird enter:
# cd /opt/thunderbird/thunderbird
# ./thunderbird

You can simply create a icon to launch the Mozilla Thunderbird from your desktop.

Simply Right click on your desktop
Select Create Launcher
Fill the necessary details as follows:

Set name to : Thunderbird
Set command to : /opt/thunderbird/thunderbird
Set comment to : My Email Client
Hit OK to create an ICON

Bash(bourne again shell)

2009-11-29T23:04:00.000-08:00

The bourne again shell(bash) is a user interface for the Linux operating system. Bash can be used to run program, manage files, interact with hardware through the Linux kernel. Shell such as bash are also known as command line interpreters in which a user inputs the commands and it responses to specific command such as ls, cd or cp. Linux is case sensitive. The main advantages of bash is it keeps history of the previous commands and completes a longer command with ease.

Features:-

1.Interactivity And History
Allows to run through previous and current commands use basic keys such as the home, arrow keys, Use the up and down keys to repeat the previous commands.
Other way is if you remember first letter of recent command use the exclamation point(!) followed by character to recall the earlier command.

2. Command Completion
The bash shell allows you to complete command by only partly typing it and using the . For example. To use ypdomainname command to find the NIS domain name for your system, type

#ypd

Now when you press tab key it completes the command for you. If there is more than one command starting with ypd, press again, to see list of these commands.

umask

2009-11-25T18:22:00.000-08:00

As Linux has the permission for all files and directories and each user can use a file according to the permissions assigned to him. This is increases the security feature of the Linux and make it more suitable for secure computing over the web.

Now when you create a new file or directory, the permissions you get depends on the value of what is known as the umask. Just simply type the umask at the command-line interface and notice the numeric masked value of the permissions:

#umask
0022
This number gives the values of the permission but in order to understand this you need to have the clear idea of the numeric value of the permissions. The first number (0) in the umask is currently unused. So this means the actual umask is 022.

Now if everyone has the permissions to your files and directory i.e read, write and execute so it corresponds to the number 7(r+w+x = 4+2+1). If you apply it to all the users than it corresponds to 777.

By convention the permission of 777 corresponds to the umask of 000. But However, umask does not allow to configure execute(x=1) permissions on any file. Now if we again consider the 022 value it will correspond to the permission of 644(rw+w+w does"t provide execute permission), or rw-r--r--; this means the owner has the read and write permissions, the member of the group that own the file have read permissions, and all others users have read permissions.

About LDAP

2009-11-10T06:28:00.000-08:00

LDAP stands for Lightweight Directory Access Protocol. It is application protocol used for querying and modifying the directory services which run over TCP/IP. The LDAP is used by programs like e-mail and other programs to look an information from a server. "LDAP-aware" client programs are used to query the LDAP servers to look up the desired entries in a number of ways. LDAP servers indexes all the data in their entries, and the "filters" are used to select the desired data and return the desired information only.

Take an example translated in the plain english- "Search for all the people located in washington whose name contain "john" that have the e-mail address . Return their full name, contact number, description, e-mail, title and work-profile.

LDAP are used for the encryption certificates, pointers to printers and other services available over the network. LDAP can be used for any kind of directory-like information, where you require the fast lookups and less-frequent updates.

As LDAP is a protocol, LDAP doesn"t define how the programs work on either the client or server side what It defines is the "language" used by client programs to talk to servers (and servers to servers).It is possible that on the client side, a client may be an email program, a printer browser, or an address book. LDAP doesn"t includes the security or encryption, so updates usually requires the additional protection such as an encrypted SSL(Secure Shell) connection to the LDAP server.

LDAP also defines: Permissions, which are set by the administrator to allow only certain group of people to access the LDAP database, and optionally keep certain data private.

The LDAP server daemon is refered as Slapd. Slapd supports a variety of different database backends which can be used with it.

These includes the primary choice BDB, which is a high-performance transactional database backend; LDBM, a lightweight DBM based backend; SHELL, a backend interface to arbitrary shell scripts and PASSWD, a simple backend interface to the passwd file.

Linux ARP And Commands

2009-11-09T05:11:00.000-08:00

The (ARP) stands for Address Resolution Protocol. The ARP work is to define the define the network interfaces connected to an ethernet media segment (hardware addresses) to map an IP address (logical addresses assigned to machines) to a link layer address which it do on demand. The link layer address is the correct term although it is interchangeably used with Ethernet addresses, Media Access Control (MAC) addresses.

ARP is commonly used to translate the protocol addresses to hardware interface addresses. Modifying the ARP cache can change which interfaces handles the specific requests. ARP cache entries may be marked with the following flags:
C (complete), M (permanent), and P (publish)

While arp can create a proxy for a single system, subnet proxies can be handled by the arp kernel module.

arp [-evn] [-H type] [-i if] -a [hostname]
arp [-v] [-i if] -d hostname [pub]
arp [-v] [-H type] [-i if] -s hostname hw_addr [temp]
arp [-v] [-H type] [-i if] -s hostname hw_addr [netmask nm] pub
arp [-v] [-H type] [-i if] -Ds hostname ifa [netmask nm] pub
arp [-vnD] [-H type] [-i if] -f [filename]

-a [hosts] , --display [hosts] It displays the entries for hosts, if none of them are specified, all entries.

-d host [pub] , --delete host [pub] Removes the specified host's entry. To delete a proxy entry, add the pub argument and specify the interface associated with the proxy using -i.

-D, --use-device Use the hardware address associated with the specified interface. This may be used with -s when creating a proxy entry.

-f file, --file file Read the entries from a file and add them.

-H type, --hw-type type, -t type Search for type entries when examining the ARP cache. type is usually ether (Ethernet), which is the default, but may be ax25 (AX.25 packet radio), arcnet (ARCnet), pronet (PROnet), or netrom (NET/ROM).

-i interface, --device interface Select an interface. If you need to dump the ARP cache, this option will cause the command to display the entries using that interface. When setting entries, this will cause the interface to be associated with that entry. If you do not use this option when setting an entry, the kernel will guess.

-n, --numeric Display host IP addresses instead of their domain names.

-s host hardware-address [netmask mask] [pub] , --set host hardware-address [pub] It Adds a permanent entry for host at hardware-address. A hardware-address for type ether hardware is 6 hexadecimal bytes, colon-separated. The pub argument can be used to set the publish flag, creating a proxy entry.

-v, --verbose Verbose mode.

Here are all the possible states for entries in the neighbor table.

Table 2.1. Active ARP cache entry states

ARP cache entry state	meaning	action if used
permanent	never expires; never verified	reset use counter
noarp	normal expiration; never verified	reset use counter
reachable	normal expiration	reset use counter
stale	still usable; needs verification	reset use counter; change state to delay
delay	schedule ARP request; needs verification	reset use counter
probe	sending ARP request	reset use counter
incomplete	first ARP request sent	send ARP request
failed	no response received	send ARP request

Understanding ext3 file system and its advantages

2009-11-02T19:21:00.000-08:00

The ext2 file system of Linux is a well-tested subsystem and very well optimized. But as of now, the other file systems that were in there experimental stage when ext2 was created have optimized, tested, matured and have become available for Linux.

There are four file systems which one might consider to replace the aging ext2 with: ext3, ReiserFS, XFS, and JFS. All the four of these file systems offers features that might be tempting in various circumstances, but the most important enhancement offered by all the four is called journaling. Considering the Traditional file systems (such as ext2) must search through the directory structure and find the right place on disk to lay out the data, and then lay out the data. (Linux is capable of cache the whole process mentioned above, including the directory updates and thereby making the process faster to the user.)

The problem with this method is that in the event of an unexpected crash of Operating system due to some reasons, the fsck program has to go in and follow up on all of the files that are on the disk in order to make sure that they don’t contain any dangling references (for example, i-nodes that point to other, invalid i-nodes or data blocks). As the disks expands in size and shrink in price, the availability of these large capacity disks means more of us will have to deal with the aftermath of having to fsck a large disk. And anyone who had done that before can tell you, it isn’t fun. The process can take long time to complete, and that means downtime for your users, which is not exceptable in the organizations .

With journaling file systems, the new way of getting data out to disk, instead of finding the right place, the file system simply writes the data out in any order it can, as fast as it can. Each time, it logs the location of these data blocks.For eg:- You can think of it as being like using the same spiral notebook for multiple classes without prepartitioning the notebook. It would be wiser to simply take notes for each class in chronological order instead of grouping all of one class together. A journaled file system is like such a notebook, with the beginning of the notebook containing an index telling you which pages contain all the notes for a single class. Once the data is written, the file system can go move things around to make them optimal for reading without risking the integrity of the file.

This means to you as a system administrator is that the amount of time it takes for the disk to write out data is much less, while at the same time the safety of getting the data written out to disk quickly means that in the event of a system crash, you won’t need to run fsck exhaustively under pressure. Even when you do run fsck, it only has to check recently modified data, so instead of interminable times, you’ll find that the checks go very quickly.

So the last question arises, which of the four journaling systems should you choose? That is entirely up to you. But the only one we have discussed is ext3, which is the default file system in Red Hat Linux.

Concept of the i-Nodes and Superblocks in Linux/Unix System

2009-10-29T05:54:00.000-07:00

The fundamental building block of UNIX file systems (including Linux’s ext2/ext3) is the i-node. An i-node is a control structure that points either to the other i-nodes or to data blocks.

The control information in the i-node includes the file’s owner, permissions, size, time of last access, creation time, group ID, etc. ( the entire kernel data structure is available in /usr/src/linux/include/linux/ext3_fs.h—assuming, of course, that you have the source tree installed in the /usr/src directory.) The one thing that an i-node doesn"t keep is the file’s name.

While the directories themselves are special instances of the files. And this means that each directory gets an i-node, and further the i-node points to data blocks containing information (filenames and i-nodes) about the files in the directory. The i-nodes are used to provide the indirection so that more data blocks can be pointed to—which is reason why each i-node does not
contains the filename. (Only one i-node works as a representative for the entire file which contains the filename; thus it would be a waste of the space if every i-node contains the filename information.) Each indirect block can be used to point in turn to other indirect blocks if necessary.

Superblocks:-
The very first information which is read from a disk is its superblock. This small data structure reveals the several key pieces of the information, which includes the disk’s geometry, the amount of available space, and, most important of the all, the location of the first i-node. In the absence of a superblock, a file system is useless.

Something as important as the superblock cannot be left to the chance. Thus the Multiple copies of this data structure are scattered all over the disk to provide backup in case the one is damaged. Under the Linux’s ext2 file system, a superblock is placed after every group of blocks, which contains an i-nodes and data. One group consists of 8,192 blocks; thus this means the first redundant superblock is at 8193, the second at 16385, and so on.

Remote Shell: rsh

2009-10-28T19:56:00.000-07:00

As you might have seen with telnet, that you must enter a username and password in order to log on to another host. This may not work out well for those people who need to remotely log in to other hosts often . They want that the other host automatically to trust them so that when issued a remote login request, the system would allow them access without asking for a login and password.

The double-win has a feature like that and has the ability to automate tasks that require one host to invoke a program on another host.

To accommodate this in Linux, the rsh command was created. In its simplest form, specify the name of the host you wish to log in to, same as the way you would do for telnet. For example:
[rwhite@workbox rwhite]$ rsh gregory

If you have set up your configuration files so that gregory knows to trust you, the system will automatically give you a shell prompt. If the configuration file does not automatically trust you, you will need to enter your password again.

To set up the configuration file, edit the .rhosts file ( there is a period in front of the filename) in your home directory. Open the .rhosts file and create a line that looks like this:
host_to_trust your_username

And If you want to rsh from workbox to gregory without being prompted for a password, create the following file in an .rhosts file in your home directory on gregory:
workbox rwhite

And thats it you are ready to go!

The rsh enables you to login remotely at shell prompt of other server but than again there is a utility known as ssh(secure shell client). Just have a look at that too and than decide which one you would like to use.

Languages Internal/external to Oracle database and developers suite

2009-10-21T09:00:00.000-07:00

The SQL is a language which cannot be avoided in accessing a database but it can”t be used alone by itself to develop the applications as it does not have facilities for developing the user interfaces and lacks the procedural structures needed for manipulating rows individually.

PL/SQL is a proprietary language to Oracle. PL/SQL has the usual procedural constructs (such as conditional branching based on if-then-else and iterative looping) and facilities for user interface design. With the PL/SQL code calls can be embed to SQL. PL/SQL application have the ability to use SQL to retrieve one or more rows from the database, then perform various actions based on their content, and then issue more SQL to write rows back to the database.

The other languages are also available which run external to the database such as C or Java and also many 3GL languages can also be used. For most of the languages oracle provides the OCI (Oracle Call Interface) libraries which let the code written in these languages to connect to the database and invoke the SQL commands. But remember that these libraries are proprietary to the Oracle which means the code would run for oracle database only and would have to be rewritten for it to run on other database but Java applications can avoid this problem. So it is quite clear that many organizations will not want to use the 3GL to develop the applications for database. Due to this Oracle Corporation provides application development tools as part of the Oracle Developer Suite. With these tools the programmers can be far more productive than if they were working with a 3GL.

Linux text to speech festival

2009-10-15T21:03:00.000-07:00

About Festival:-
The festival is a application that lets you text-to-speech (TTS) synthesis in unix like system. Festival is basically a free software framework for the Unix Like system that can convert the plain tet into audible speech which you can hear from your speakers. The festival can work on Uni like system if configured through an rpm package while on RedHat/Centos you can simply install it via yum. Apart from this there are also other text to speech applications are available but as a beginner you can start with the festival. This text to speech reader can also be used in reading the pdf document by using applications like kpdf or adobe, so again you will not be needing to stare at your screen for reading a ebook or so just use this reader, it will do it all for you.

First check that if any festival package is installed or not just type the following command at your terminal:
# which festival

the above command shows that festival isn"t installed.

than just give the following command
#yum install festival

thats it you"re done, yum will now communicate with the repositories of CentOS and resolve all the dependencies and software for you.

Next just try playing a text with it with following command.
#echo "you have finally configured festival bookmark linuxadministrationguide site now" | festival --tts

Installing vlc player in Fedora/Red Hat/ CentOS

2009-10-15T09:22:00.000-07:00

VLC Player:-
Video Lan is one of the most popular and famous media player which supoort various file types and can play almost ll types of file from .wmv, 3gp, mp3 and many others. VLC is also available for various linux. You can download it from here according to your distros and for fedora, Red Hat and CentOS you can simply download through yum by issuing the following command

# yum install vlc

Yum will download all the dependencies and relevant files which are needed for using the vlc. However, note that you cant open the vlc as the root user this is due to the security purposes. You must login through another user to use it and you should always login through a user always and use root account only when you don"t have other option.

Virtualization Grid Computing

2009-10-15T01:46:00.000-07:00

The concept of the grid deals critically with the virtualization, which means that at all levels there exist a layer of the abstraction as to what is requested and what is provided(service).Grid computing makes it possible to create a single IT infrastructure that can be shared by multiple business processes.

This can be better understand by considering an Oracle"s Grid environment, where the end users as for an application service and the grid works out as to which clustered J2EE application server can best provide it.

Consider an Oracle application server model in which an Application server asks for the database service from an RAC database and Grid work out from which RAC instance the data service can best be provided. Within the Grid there is indexing of all the possible services to available service provider and the algorithms for assinging the worload and resource appropriately. Due to this the end user neither needs nor have the capacity to know from where the computing resources are actually being provided.

The Grid is not only exclusive to Oracle but at the physical level, some O.S and hardware vendors have the capabilities to partition the server into virtual machines, which can be alloted RAM and CPUs dynamically according to the demand. Thus it is conceptually similar to the Oracle"s approach of dynamically assinging application server and database server resources. Thus there is no reason for which the two approaches can"t be combined and work towards the same goal and can work together. The result of a such a approach would be an environment where adequate resources will always be available on demand, without facing the issues of excess capacity or underperformance at times. It should be possible to design a Grid environment with no single point of failure, and thus achieving 100% uptime, which is demanded by many organizations.

The Oracle"s Application Server

2009-10-09T02:27:00.000-07:00

Understanding Need
The need for application servers has come with the potential realization of the Web as the standard platform for delivering the applications to end users. An application server has replaced the client-side software which is traditionally installed on end-user computers: it runs applications centrally on the server and presents it to users by displaying it locally in web browsers like mozilla, internet explorer. These applications make use of the data stored in one or more database servers.

Model
Oracle Application Server provides a platform for developing, deploying, and managing web applications. A web application is any application with which
users communicate via HTTP. Web applications usually run in at least three tiers environment:First is a database tier which manages access to the data, the client tier which is often implemented as a web browser and handles the local window management(web browser here) for communications with the users, and an application tier in the middle of the two which executes the program logic that generates the user interface transferred to the browser of user and the SQL calls to the database. This is the model by which corporate companies provides its services to the users over internet and thus you can realize the need of an application server.

Advantages, Conforming standards and contribution to grid
For developing Web applications there are a number of technologies, among which most dominant today is Java. Applications which are written in Java should conform to the J2EE (Java 2 Enterprise Edition) standard, which defines how the java applications should be packaged and deployed. J2EE standards are controlled by Sun Microsystems(currently takeover by Oracle corporation) and accepted virtually by all major software developers. Oracle Application
Server is a fully J2EE-compliant application server. Oracle’s implementation of the standards has allowed the automatic load balancing and fault tolerance across the multiple application servers on multiple machines though J2EE clustering. The clustering virtualizes the provision of the application service i.e. users ask for an application, which may be available from a number of locations, the cluster works out from where the session or request can best be serviced. If one location fails due to some error, others can take up the load, and thus the more resources can be made available for an application as necessary. Oracle Application Server’s has majorly contributed to the Grid with the ability to separate the request for a service from the location provision and adding or removing the J2EE servers from a cluster dynamically.

Global Approach
Oracle has commitment to the international standards i.e. Applications which are running in the Oracle Application Server environment can connect to any databases which has the Java-compliant drivers which means it is not necessary to use an Oracle database only. Applications which are developed with the Oracle Application Server toolkits can be deployed to a third-party J2EE-compliant application server. Although, the Oracle product set is particularly powerful and will often be the best choice.

Connection pooling model
For the connection with the database generally connection pooling model is used instead a one-for-one mapping of end-user session as it is more efficient. In connection pooling, the application server establishes a small number of persistent database sessions and makes them available on demand (queuing requests if necessary) to a relatively large number of end-user sessions against the application server.

Opening And Extracting .rar Files in Linux/Unix system

2009-10-08T09:51:00.000-07:00

Rar is a very famous compression technique used for compressing the file. Most files from internet can be downloaded from internet in the form of zip or rar files. But unlike zip for which we can directly use the unzip command same can"t be follow until you install unrar utility.

RAR is a proprietary file format for data compression and archiving which is developed by Eugene Roshal. You can find the official site in here.

Under Linux and Unix OS the command used is unrar but since by default unrar is not installed on the OS , so you need to install it with the help of yum command.

For Fedora Linux you can simply install it with the help of the Yum whose command is as follows
#yum install unrar

Another way which i used to install the package is directly downloading from its site. You can download it from here

since the file you downloaded is in gunzip format use;
# tar -zxvf rarlinux-3.6.0.tar.gz

when you use above command it will show you output like

rar/
rar/file_id.diz
rar/license.txt
rar/Makefile
rar/order.htm
rar/rarfiles.lst
rar/rar.txt
rar/readme.txt
rar/technote.txt
rar/whatsnew.txt
rar/rar
rar/rar_static
rar/unrar
rar/default.sfx

do ls it would have now created a rar subdirectory. just go to rar directory as follows:-

$ cd rar $ ./unrar

Now copy rar and unrar to /bin directory:
# cp rar unrar /bin

that is you are done now go and open your file with following command:
$ unrar e file.rar

Option with rar	Description
unrar l filename.rar	List file inside rar archive
unrar x filename.rar	Open (x) files
unrar t filename.rar	Test the integrity of the archieve

Install WEBMIN to Graphically Administer Your Linux Server

2009-10-07T06:34:00.000-07:00

Although Red Hat includes all tools and packages required for system administration ,One of the popular system management tool available under Linux and UNIX is called Webmin. It works with a Graphical environment within your browser.

Introduction:-
Webmin provides a variety of functionality for administrators, especially for those who want to manage multiple servers at work. Installing Webmin can be useful for a wide variety of reasons some of which are:-

Easy to setup user accounts and configuring quota and rights etc
Setup Apache, DNS, file sharing and much more with ease
With Webmin you do not need to manually edit Unix/Linux configuration files like /etc/passwd.
Helps you manage a system from the console or remotely.

If you like to check the modules included in a standard edition you can have a look here

Installing WEBMIN:-
Step by Step Guide

1. Go to the Webmin site at http://webadmin.sourceforge.net./download.html and download the latest webmin software suitable to your Linux distribution in my case its CentOS so i downloaded the noarch.rpm whose version is 1.490 .

2. Install the Webmin RPM package using rpm –U. (specify the name of the RPM package file.)
# rpm -U webmin-1.490-1.noarch.rpm

3. The Webmin package will determine the operating system version being run, and then install its contents. When installation is finished, you will be presented with a address that you should put in a web browser like mozilla firefox to log in to Webmin as root .

4. Point your browser to http://yourservername:10000 and log in using the root account and its password, . Set yourservername to be the name of the server as described by the Webmin installation message.

5. Go have a look around with Webmin, explore and see what options are available to you.

Tracking Processes In UNIX/LINUX System

2009-10-06T03:31:00.000-07:00

In Linux (and UNIX in general), each program which is running comprises a process.From the operating system’s point of view, each process is independent of the others. Unless it specifically asks to share resources with other processes, a process is confined to the memory and CPU allocation assigned to it. If a Process oversteps its memory allocation and could corrupt another running program and make the system unstable are immediately killed by Linux. This method of handling processes has resulted as a major contributor to the stability of UNIX/LINUX systems: User applications cannot corrupt other user programs or the operating system.
                    There are tools provided by which you can manually list and manipulate processes. These are very important elements of a system administrator’s daily work.

Command used for Listing Processes: ps
               The ps command lists all the processes in a system, their state, size, name, owner, CPU time, wall clock time, and much more. There are many command-line parameters available; the majoy one are

Options for ps	Description
–a	Shows all the processes with a controlling terminal and not just the current user’s processes.
–r	Show only running processes
–x	Show processes that do not have a controlling terminal.
–u	Show the process owners.
–f	Display parent/child relationships among processes.
–l	Produce a list in long format.
–w	Shows a process command-line parameters (up to half a line).
–ww	Show all of a process’s command-line parameters.

The most commonly used parameters used with ps command is –auxww. These parameters show all the processes (regardless of whether they have a controlling terminal),each process’s owners, and all the processes’ command-line parameters.

Brief Introduction To Oracle And Database Management System

2009-10-05T19:30:00.000-07:00

About ORACLE:-
The oracle is the global leaders in the field of software and provides solutions for every tier of business. It specializes the enterprise software products particularly "Database Management Systems". It was founded in 1977 by the CEO of oracle corporation LARRY ELLISON. Oracle has the third largest software revenue after IBM and Microsoft. The company is well known for its database and provides a number of other products including database development, middle-tier software, enterprise resource planning software (ERP), customer relationship management software (CRM) and supply chain management (SCM) software. The Oracle database is Relational database management system(RDMS).

DATABASE:-
In most simple form, a database is a mechanism for storing the data. This data may be logical like values stored in computer program, or may be physical like a file.

Types Of Database:-

Hierarchical
Network
Relational

The Oracle is a Relational Database Management System(RDBMS).

Relational Model:-
In it the data is broken into the collection of objects and relations that store the actual data. The database contains many table and the data in it is related with other tables data. The Tables that have related data need not to know where related information is stored physically.
The whole Relational Model concept was first intoduced by E. F. Codd in his article of relational model which can be founded here

Querying the Database:-
RDBMS allows you to manipulate relational tables and their contents and provides a language that allows you to create , modify, remove objects in database as well as add, change and delete data. The language used is "Structured Query Language".

SQL is actually a collection of several different languages each having a particular purpose. It is made up of:

1. DATA DEFINITION LANGUAGE:-
It is used to Create and modify database objects Includes CREATE, ALTER, DROP, RENAME and TRUNCATE.

2. DATA MANIPULATION LANGUAGE:-
It is used to modify the data in the tables in the database. Includes INSERT, UPDATE and DELETE. It also includes the extensions to control the transactions in database includes COMMIT , ROLLBACK and SAVEPOINT.

3. DATA CONTROL LANGUAGE:-
It is used to Configure security to perform database tasks and Manipulate database objects . It includes GRANT and REVOKE.
3. DATA CONTROL LANGUAGE:-

Install Skype(pc2pc calling software) On Linux 64 bits

2009-10-03T07:25:00.000-07:00

Well as you must be familiar with Skype software which allows you to make pc calls to any computer worldwide connected via internet absolutely free with excellent sound quality. Not only this with credit you can even make cheap calls on phones in any country, moreover share files, chat and more.

To begin with Installation check this installation is for Red hat enterprise Linux and CentOS Enterprise Linux 64bit operating system.

1. Download the software from here
2. Once it is download open the terminal
3. Move to location were you download the setup file
4. issue the following command

#tar -xvjf skype_static-.tar.bz2
it will show you the following result-

skype_static-2.1.0.47/
skype_static-2.1.0.47/skype.conf
skype_static-2.1.0.47/skype.desktop
skype_static-2.1.0.47/README
skype_static-2.1.0.47/LICENSE
skype_static-2.1.0.47/avatars/
skype_static-2.1.0.47/avatars/Skype Boarder.png
skype_static-2.1.0.47/avatars/Fax Skype.png
skype_static-2.1.0.47/avatars/Skype-ahoy.png
skype_static-2.1.0.47/avatars/Skype Headset.png
skype_static-2.1.0.47/avatars/Skype Artiste.png
skype_static-2.1.0.47/avatars/College Skype.png
skype_static-2.1.0.47/avatars/The Skypeness.png
skype_static-2.1.0.47/avatars/Skype Extreme.png
skype_static-2.1.0.47/avatars/Chic Skype.png
skype_static-2.1.0.47/avatars/Architect Skype.png
skype_static-2.1.0.47/avatars/Devil Skype.png
skype_static-2.1.0.47/avatars/Skype Jah.png
skype_static-2.1.0.47/avatars/Metal Skype.png
skype_static-2.1.0.47/avatars/Party Skype.png
skype_static-2.1.0.47/avatars/Skype Time.png
skype_static-2.1.0.47/avatars/Travel Skype.png
skype_static-2.1.0.47/avatars/Christmas Skype.png
skype_static-2.1.0.47/avatars/Skype Aid.png
skype_static-2.1.0.47/avatars/Sushi Skype.png
skype_static-2.1.0.47/avatars/Skype Bling.png
skype_static-2.1.0.47/avatars/Rice Skype.png
skype_static-2.1.0.47/avatars/Skype.png
skype_static-2.1.0.47/avatars/Yin Yang Skype.png
skype_static-2.1.0.47/avatars/Skype Cola.png
skype_static-2.1.0.47/avatars/Skype Jyve.png
skype_static-2.1.0.47/avatars/Call Me Sweetheart.png
skype_static-2.1.0.47/avatars/Star Skype.png
skype_static-2.1.0.47/avatars/Make Skype Not War.png
skype_static-2.1.0.47/avatars/Skype 502.png
skype_static-2.1.0.47/avatars/Skype-a-Manger.png
skype_static-2.1.0.47/avatars/Wetsuit Skype.png
skype_static-2.1.0.47/avatars/Earbud Skype.png
skype_static-2.1.0.47/avatars/Beach Skype.png
skype_static-2.1.0.47/avatars/Skype Smiley.png
skype_static-2.1.0.47/avatars/Skype-in-one.png
skype_static-2.1.0.47/avatars/Skypers of the Caribbean.png
skype_static-2.1.0.47/avatars/Geisha Skype.png
skype_static-2.1.0.47/avatars/Designer Skype.png
skype_static-2.1.0.47/avatars/Ninja Skype.png
skype_static-2.1.0.47/avatars/Pop Skype.png
skype_static-2.1.0.47/avatars/Skype Candy.png
skype_static-2.1.0.47/avatars/DJ Skype.png
skype_static-2.1.0.47/avatars/Business Skype.png
skype_static-2.1.0.47/avatars/Skype Safety.png
skype_static-2.1.0.47/avatars/Behind Skype.png
skype_static-2.1.0.47/avatars/Hula Skype.png
skype_static-2.1.0.47/avatars/Skype Beauty.png
skype_static-2.1.0.47/avatars/Skype Shorty.png
skype_static-2.1.0.47/avatars/Skypahontas.png
skype_static-2.1.0.47/avatars/Carnaval Skype.png
skype_static-2.1.0.47/avatars/Skype Goaaaaal.png
skype_static-2.1.0.47/avatars/Desert Skype.png
skype_static-2.1.0.47/avatars/Angel Skype.png
skype_static-2.1.0.47/avatars/DIY Skype.png
skype_static-2.1.0.47/avatars/Skype Cool Shades.png
skype_static-2.1.0.47/avatars/Skype in a Bag.png
skype_static-2.1.0.47/avatars/Skype San.png
skype_static-2.1.0.47/avatars/Skype Brrr... .png
skype_static-2.1.0.47/avatars/Call Me.png
skype_static-2.1.0.47/avatars/Empire Skype.png
skype_static-2.1.0.47/lang/
skype_static-2.1.0.47/lang/skype_it.ts
skype_static-2.1.0.47/lang/skype_th.ts
skype_static-2.1.0.47/lang/skype_pl.ts
skype_static-2.1.0.47/lang/skype_ko.ts
skype_static-2.1.0.47/lang/skype_et.ts
skype_static-2.1.0.47/lang/skype_fr.ts
skype_static-2.1.0.47/lang/skype_es.ts
skype_static-2.1.0.47/lang/skype_pt_br.ts
skype_static-2.1.0.47/lang/skype_zh_t.ts
skype_static-2.1.0.47/lang/skype_zh_s.ts
skype_static-2.1.0.47/lang/skype_en.ts
skype_static-2.1.0.47/lang/skype_ja.ts
skype_static-2.1.0.47/lang/skype_de.ts
skype_static-2.1.0.47/lang/skype_bg.ts
skype_static-2.1.0.47/lang/skype_ru.ts
skype_static-2.1.0.47/lang/skype_pt_pt.ts
skype_static-2.1.0.47/lang/skype_tr.ts
skype_static-2.1.0.47/lang/skype_lv.ts
skype_static-2.1.0.47/lang/skype_ro.ts
skype_static-2.1.0.47/lang/skype_lt.ts
skype_static-2.1.0.47/lang/skype_bg.qm
skype_static-2.1.0.47/lang/skype_de.qm
skype_static-2.1.0.47/lang/skype_en.qm
skype_static-2.1.0.47/lang/skype_es.qm
skype_static-2.1.0.47/lang/skype_et.qm
skype_static-2.1.0.47/lang/skype_fr.qm
skype_static-2.1.0.47/lang/skype_it.qm
skype_static-2.1.0.47/lang/skype_ja.qm
skype_static-2.1.0.47/lang/skype_ko.qm
skype_static-2.1.0.47/lang/skype_lt.qm
skype_static-2.1.0.47/lang/skype_lv.qm
skype_static-2.1.0.47/lang/skype_pl.qm
skype_static-2.1.0.47/lang/skype_pt_br.qm
skype_static-2.1.0.47/lang/skype_pt_pt.qm
skype_static-2.1.0.47/lang/skype_ro.qm
skype_static-2.1.0.47/lang/skype_ru.qm
skype_static-2.1.0.47/lang/skype_th.qm
skype_static-2.1.0.47/lang/skype_tr.qm
skype_static-2.1.0.47/lang/skype_zh_s.qm
skype_static-2.1.0.47/lang/skype_zh_t.qm
skype_static-2.1.0.47/sounds/
skype_static-2.1.0.47/sounds/CallHold.wav
skype_static-2.1.0.47/sounds/CallRingingOut.wav
skype_static-2.1.0.47/sounds/CallFailed.wav
skype_static-2.1.0.47/sounds/CallRingingIn.wav
skype_static-2.1.0.47/sounds/VoicemailReceived.wav
skype_static-2.1.0.47/sounds/CallBusy.wav
skype_static-2.1.0.47/sounds/CallHangup.wav
skype_static-2.1.0.47/sounds/ContactAdded.wav
skype_static-2.1.0.47/sounds/ChatIncomingInitial.wav
skype_static-2.1.0.47/sounds/TransferComplete.wav
skype_static-2.1.0.47/sounds/ChatIncoming.wav
skype_static-2.1.0.47/sounds/ContactOnline.wav
skype_static-2.1.0.47/sounds/ContactOffline.wav
skype_static-2.1.0.47/sounds/TransferRequest.wav
skype_static-2.1.0.47/sounds/CallResume.wav
skype_static-2.1.0.47/sounds/ChatOutgoing.wav
skype_static-2.1.0.47/sounds/CallRemoteHangup.wav
skype_static-2.1.0.47/sounds/TransferFailed.wav
skype_static-2.1.0.47/sounds/ContactAuthRequest.wav
skype_static-2.1.0.47/sounds/SkypeLogout.wav
skype_static-2.1.0.47/sounds/SkypeLogin.wav
skype_static-2.1.0.47/sounds/CallConnecting.wav
skype_static-2.1.0.47/icons/
skype_static-2.1.0.47/icons/SkypeBlue_48x48.png
skype_static-2.1.0.47/icons/SkypeBlue_32x32.png
skype_static-2.1.0.47/icons/SkypeBlue_16x16.png
skype_static-2.1.0.47/skype

5. After this check our it would have created a directory of kype_version issue the following command to move to this directory

#cd skype_static-

6. Now you can run skype by issuing following command

#./skype

7. Now if you want to make it available to other users on system also than use
following commands

# mkdir /usr/share/skype
# cp -a * /usr/share/skype/
# cd /usr/share/skype/
# mv skype /usr/bin/
# mv skype.conf /etc/dbus-1/system.d/
# chown . skype.desktop
# mv skype.desktop ~/Desktop

Basics of User and Group Management

2009-10-01T10:04:00.000-07:00

Everyone on Linux server requires an user account. Every account has its rights and privileges associated with it, which vary depending on the command and the directory. Maintaining and Organizing each user account can be difficult if you have large number of users in an organization, so Linux user groups are organized into groups. While default users are member of their default groups, users can be organize into new groups, and rights and priviledges varies differently by group.

In Red Hat Linux, user accounts are organized in /etc/passwd. Passwords are made more secure in /etc/shadow. For Red Hat Linux groups, the analogous files are /etc/group and /etc/gshadow.

While creation of new account, the default parameters are configured in /etc/login.defs; configuration files are normally copied to the new user"s home directory from the /etc/skel directory.

Install Vuze(Azureus) Bittorent client on Linux 64 bit

2009-09-29T09:40:00.000-07:00

About Vuze:-
Vuze is torrent p2p client which helps you to download files across various torrents present world wide. Obviously there are other clients like bittorrent and more but Vuze is one of the best choice for Linux and also because i never faced any problem with it.

So here are the steps how i installed vuze on my CentOS 5.3 which is a 64 bit OS:-
Note:- You must have Java Runtime Environment installed already before installing Vuze.

1. Download the vuze software by visiting here. Choose Linux AMD64 as shown in screen

2. Save it on Desktop or were ever you like.

3. If you are not Login as root check for appropriate permissions.

4. Move to location were your software is initially installed i.e. Desktop in my case.

5.open terminal and type following command

# cd /root/Desktop

# ls

you will see here a file as: "Vuze_4.2.0.8_linux-x86_64.tar.bz2"

6. To run this .tar.bz2 file use the following command:-

# tar -jxvf filename.tar.bz2
in this case it is
# tar -jxvf Vuze_4.2.0.8_linux-x86_64.tar.bz2

7.You will see files like:

vuze/
vuze/Azureus2.jar
vuze/GPL.txt
vuze/README.txt
vuze/TOS.txt
vuze/azureus
vuze/plugins/
vuze/plugins/azplugins/
vuze/plugins/azplugins/azplugins_2.1.6.jar
vuze/plugins/azrating/
vuze/plugins/azrating/azrating_1.3.1.jar
vuze/plugins/azupdater/
vuze/plugins/azupdater/Updater.jar
vuze/plugins/azupdater/azureus.sig
vuze/plugins/azupdater/plugin.properties
vuze/plugins/azupdater/azupdaterpatcher_1.8.8.jar
vuze/plugins/azupnpav/
vuze/plugins/azupnpav/azureus.sig
vuze/plugins/azupnpav/plugin.properties
vuze/plugins/azupnpav/azupnpav_0.2.23.jar
vuze/swt.jar
vuze/updateAzureus
vuze/installer.log
vuze/vuze
vuze/vuze.png
vuze/ChangeLog.txt

8. Now use following command:

# cd Vuze

9. Once you are in type following command:

# ls
output of this would be like

azureus       ChangeLog.txt installer.log README.txt TOS.txt        vuze
Azureus2.jar GPL.txt        plugins        swt.jar     updateAzureus vuze.png

10. Now it is simple you just need to execute azureus file as

# ./azureus
what you will see now would be like

Starting Azureus...
Java is GCJ.. looking for Sun Java..
Java exec not found in PATH, starting auto-search...
Java exec found in /usr/java/latest/bin/
Suitable java version found [/usr/java/latest/bin/java = 1.6.0_16]
Configuring environment...
find: /root/.azureus/plugins: No such file or directory
Browser check failed with: InvocationTargetException, No more handles [Unknown Mozilla path (MOZILLA_FIVE_HOME not set)]
Auto-scanning for GRE/XULRunner. You can skip this by appending the GRE path to LD_LIBRARY_PATH and setting MOZILLA_FIVE_HOME.
checking /etc/gre.d/gre64.conf for GRE_PATH
GRE found at /usr/lib64/xulrunner-1.9.
setting LD_LIBRARY_PATH to: /usr/lib64/xulrunner-1.9
setting MOZILLA_FIVE_HOME to: /usr/lib64/xulrunner-1.9
Loading Azureus:
/usr/java/latest/bin/java -Xmx128m -cp "./Azureus2.jar:./swt.jar" -Djava.library.path="/root/Desktop/vuze" -Dazureus.install.path="/root/Desktop/vuze" -Dazureus.script="./azureus" -Dazureus.script.version=2 org.gudy.azureus2.ui.swt.Main
file:/root/Desktop/vuze/Azureus2.jar ; file:/root/Desktop/vuze/swt.jar ; file:/root/Desktop/vuze/
changeLocale: *Default Language* != English (United States). Searching without country..
changeLocale: Searching for language English in *any* country..
changeLocale: no message properties for Locale 'English (United States)' (en_US), using 'English (default)'
UIFunctions/ImageLoad took 32ms
new shell took 180ms
new shell setup took 38ms
skinlisteners init took 30ms
skin init took 83ms
MainMenu init took 166ms
createWindow init took 0ms
skin layout took 33ms
pre skin widgets init took 0ms
hooks init took 0ms
WARNING: already added UIUpdatable com.aelitis.azureus.ui.swt.views.skin.sidebar.SideBar@11568fb5
skin widgets (1/2) init took 201ms
skin widgets init took 111ms
pre SWTInstance init took 0ms
Init Core Columns took 68ms
SWTInstance init took 0ms
shell.layout took 0ms
---------SHOWN AT 1254240341193;1179ms
---------DONE DISPATCH AT 1254240342228;2214ms
---------READY AT 1254240342265;2251ms
shell.open took 1072ms
processStartupDMS took 0ms
vuzeactivities init took 0ms
Locale Initializing took 39ms
11498:    Core: 100ms for activity between 'Initializing Global Torrent Manager' and 'Loading Plugin: azupnpav'
11530:    Core: 59ms for activity between 'Loading Plugin: azupnpav' and 'Loading Plugin: azplugins'
11575:    Core: 16ms for activity between 'Loading Plugin: azupdater' and 'Loading Plugin: Start/Stop Rules'
11737:    Core: 96ms for activity between 'Loading Plugin: Buddy' and 'Initializing Plugin: Tracker Static Pages'
11737:    Core: 96ms for activity between 'Loading Plugin: Buddy' and 'Initializing Plugin: UPnP Media Server'
11769:    Core: 40ms for activity between 'Initializing Plugin: UPnP Media Server' and 'Initializing Plugin: Rating'
11802:    Core: 32ms for activity between 'Initializing Plugin: Universal Plug and Play (UPnP)' and 'Initializing Plugin: Distributed DB'
11899:    Core: 67ms for activity between 'Initializing Plugin: Friends' and 'Loading Plugin: azupnpav'
DEBUG::Tue Sep 29 21:50:43 NPT 2009::com.aelitis.azureus.core.impl.AzureusCoreImpl::start::1092:
Core Start Complete
    Initializer::run::383,Initializer::run::135,SWTThread$2::runSupport::179,AERunnable::run::38,Thread::run::-1
Core Initializing took 783ms

11. And what now your Vuze is ready to start go and download something and dont forget to remove vuze download file from desktop if you dont want the software to consume your extra disk.

12. Now in Linux you cannot provoke vuze by simply clicking .torrent file, when you do so it will ask you what program to use. So instead i use following procedure. Go to directory where your Azureus files are located and run vuze by using

# ./vuze

once vuze is opened, select file< open

Click on Add Url
Enter the Url of torrent file
Set the Path were you want to download the file default it is /root/Azureus Downloads.
click ok
Thats it your file is now being downloaded

If you still face any issues feel free to pose comment below.

NFS Overview

2009-09-29T03:02:00.000-07:00

NFS is commonly used to share files across Linux and Unix Networks. It is distributed file system that enables the local access to remote disks and file systems. In a properly designed and implemented NFS installation, it is totally transparent to clients using remote file system but Provided you have appropriate network connection, can allow you to access files and directories located on another system or even in a different city or country using standard Linux commands. No special procedures such as password are required. NFS is a common popular file sharing protocol, so its clients are available for many non-UNIX operating systems, including the various Windows versions, MacOS, OS/2, MVS.

Initialization Scripts

2009-09-24T07:21:00.000-07:00

Network services like the Apache HTTP Server and DHCP(Dynamic Host Configuration Protocol ) along with other programs such as cron ( Enables users to schedule jobs to run automatically at a certain time and date, used in administration, connecting to internet and downloading e-mail) and syslog require a daemon to be running at all times. The daemon performs actions like listening for connections for a service on specific ports, making sure commands are executed at specific times, and capturing data such as log messages sent out by other programs.

Programs that require a daemon to be started have an initialization script in the /etc/rc.d/init.d/ directory. This script can also be used to run a command at boot time such as the readahead_early and readahead_later scripts, which run the readahead utility which loads the programs used at startup into memory before they are needed. It decreases the amount of time it takes to start the system. While booting a Red Hat Enterprise Linux system, the init program is run last in the kernel boot process. This program first executes the /etc/rc.d/rc.sysinit script to perform actions such as loading kernel modules for hardware support, loading the default keymap, and setting the hostname. The /etc/inittab script is run next, which then tells init which runlevel to start. The runlevel defines which services to start at boot time, or which initialization scripts to execute.

Lastly, the /etc/rc.d/rc.local script is executed. Commands can be added to this file for custom initialization. The initialization scripts enables user to start, stop, and restart services after the system has booted. These actions are performed with the service command as the root user. Each script has its own list of actions. Common actions defined include start, stop, conrestart (which stops and starts the service only if it is already running), and status.

To perform an action, use the following syntax:

service

For example, the following starts the OpenSSH service:
service sshd start

File Permissions 2

2009-09-23T08:58:00.000-07:00

This is in response to my earlier post on File permission. Read about basics of file permission in Linux in my earlier post here

Permission	Description
r	Read
w	Write
x	Execute (also gives permission to change into a directory)
X	Execute only if it is a directory or has execute permission for some user
S	Set user or group ID on execution
t	Sticky bit
u	Permission granted to user who owns the file
g	Permission granted to user in file"s group.

• The first three (r, w, x) read, write, and execute

• The “s” permission retain the user or group ID for a file created in the directory.

• To set the user ID for any new files created in the directory to the owner of the directory, use the chmod u+s command.

• To set the group ID for new files created in the directory to the directory’s group, use the chmod g+s command.

• If the sticky bit (the t permission) is set for a directory, the directory can only be unlinked or renamed by the root user or the owner of the directory. In its absence, anyone with write permission can delete or rename the directory.

• If the sticky bit is set for a directory, the permissions listing looks similar to the following (notice the t in the last set of permissions) :

drwxrwxrwt 22 root root 4096 Mar 30 10:57 /tmp

The last three permissions (u, g, o) are only used with the = operator to set permissions for the owner, group, others, equal to the existing permissions for the owner. For example, chmod g=u sets the group permissions
to the current permissions for the owner of the file.

TIP
To change permissions recursively (on all the files in a directory, all the files in its subdirectories, all the files in the subdirectories of the subdirectories, and so on) use the -R option to chmod such as chmod -R g+w output.txt.

Examples
. chmod ug+rw
Gives the user and group read and write permissions

. chmod -R g+r *
Gives the group read permissions for all files in the current directory and any files
and directories in the current directory, recursively

. chmod o-x
Does not let users who aren’t the owner or in the group change into the directory

File permissions can also be set graphically using the Nautilus file browser. From the desktop, click on the Places menu on the top panel and select Home Folder. Navigate to the file you want to view or change permissions for, right-click on it, and select Properties. Click on the Permissions tab as shown in Figure to view the existing permissions or change them.

File Permissions 1

2009-09-23T08:10:00.000-07:00

In Red Hat Enterprise Linux, all files have file permissions which determine whether a user is allowed to read, write, or execute them, for greater security.Command ls –l list the file permissions in the first column. The first column have places for 10 letters or hyphens. The first space is either a hyphen, the letter d, or the letter l. A hyphen means it is a file. The letter d denotes that the file is actually a directory and the letter l, it is a symbolic link to a directory somewhere else on the filesystem.

The next nine spaces are divided into 3 sets of three as shown in Figure. The first set of three is the read, write, and execute permissions for the owner of the file. The second set of three is the read, write, and execute permissions for anyone who belongs to the user group for the file. The last set of permissions is for anyone who has a login to the system.

So its like owner permissions-group user permissions-anonymous user permission

Within each set of permissions, r stands for read, w stands for write, and x stands for execute. If the file is a script or command, you must have execute permission to run it. The execute permission is required to change into a directory. To change file permissions, you must be the owner of the file or directory or be the root user. The chmod utility is used to modify file permissions.
The basic syntax is as follows:
chmod [ugoa][+-=] filename

For the first argument, choose one or more letters ugoa, where u stands for the user who owns the file , g stands for everyone in the file’s group, o stands for other users not in the file’s group, and a stands for all users. The difference between specifying o and a is that o changes the third set of permissions for everyone and a changes the permissions for all three sets.

The second argument must be one of +, -, or =. If the plus sign (+) is used, the permissions that follow it are added for the users and groups provided by the first argument. If the minus sign (-) is used, the permissions that follow are removed for the users and groups in the first argument. However, if the equals sign (=) is used, the file will only have the permissions being specified (the existing permissions are overwritten and not retained).

The last argument is a filename or group of filenames on which you set the permissions. Multiple filenames can be listed using the * wildcard character such as *.txt for all files ending in .txt. The third argument is the list of permissions for the users and groups from the first argument.

Read rest of this post here

Printer Configuration

2009-09-21T20:08:00.000-07:00

Configuring a printer is not covered by installation or setup agent. Red Hat Enterprise Linux uses the Common UNIX Printing System, also known as CUPS. CUPS uses the Internet Printing Protocol (IPP) to allow local printing and print sharing. The /etc/cups/ directory stores the configuration files for printing. These files can be easily managed with the Printer Configuration Tool in Red Hat Enterprise Linux.

NOTE
To start the Printer Configuration Tool, go to the System menu on the top panel and select Administration, Printing or execute the command system-config-printer. It will prompt for the root password. If no printers are available for the system, only the Server Settings view is available for selection. If local printers are configured, a Local Printers menu is available.

CUPS is the default printing system used by Red Hat Enterprise Linux, and one of its many advantages is that it uses IPP to broadcast shared printers on the network so that other systems can browse for them, select one as the default printer, and print to it without any further configuration. If any printers are broadcast on your network, they will appear in a Remote Printers menu. Figure shows a system with both local and remote printers. If a list isn’t already expanded, click on the triangle icon to the left of it.

The log files for the CUPS printing system are located in the /var/log/cups/ directory. Refer to this directory for access and error logs.

Starting and Stopping the Network

2009-09-21T06:28:00.000-07:00

If An Ethernet device is found during installation, the network is configured to start automatically at boot time unless uncheck the Activate on boot option for the device. To disable it use the chkconfig network off command. To enable it use the chkconfig network on command.

The /etc/hosts and /etc/resolv.conf are referenced each time they are used, so modifications to them take place immediately. If the hostname is modified in /etc/sysconfig/network, the change does not occur until the next reboot. To immediately change the hostname, execute the command hostname as the root user.

If you modify network settings in /etc/sysconfig/network-scripts/, the changes do not take place dynamically ,until the network is restarted or the individual device is shut down and brought back up. To restart the entire network (the loopback device and all network devices), use the command service network restart as root. To shut an individual device down and bring it back up, as root, execute the command ifdown and then ifup , where is the name of the device such as eth0.

To stop all the network devices, use the service network stop command as root. To start the network, use the command service network start as root.

Post-Installation Configuration

2009-09-19T19:44:00.000-07:00

This post is in response to my earlier post of network configuration.

The /etc/hosts file lists IP addresses and hostnames that should resolve to the IPaddresses as shown. The first one listed, 127.0.0.1, is referred to as the loopback interface and should never be removed. If some hostnames are not resolved by the DNS servers, list them with their IP addresses after the loopback device. For example, if your network consists only of a handful of systems, it might be easier to list them in the /etc/hosts file on each local system than set up a DNS server on the local network for name resolution.

CAUTION
Always be careful when listing hostnames that can be resolved by the DNS servers and those that are not under your control. If the IP address of the hostname changes, you will not be able to connect to the host because any IP addresses listed in /etc/hosts have precedence over any IP addresses resolved through the DNS servers.

/etc/hosts File
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
192.168.0.1 metropolis
192.168.0.2 louis
182.168.0.3 clark

A typical /etc/resolv.conf is shown below. Each nameserver line represents a
DNS server, and the search line specifies domain names to try if only the first part of a hostname is used. For example, if just the name infinity is used as a hostname, infinity.example.com and then infinity.example.org will be tried if the /etc/resolv.conf file in Listing 2.4 is on the system.

/etc/resolv.conf File
nameserver 192.168.0.254
nameserver 192.168.10.254
search example.com example.org

In the /etc/sysconfig/network-scripts/ directory, each network device has its own
configuration file with the filename ifcfg- such as ifcfg-eth0 for the first Ethernet device.

If the device uses DHCP to retrieve network settings, a typical /etc/sysconfig/networkscripts/ifcfg-eth0 file contains the lines as shown below.

Ethernet Interface Configuration File for DHCP
DEVICE=eth0
BOOTPROTO=dhcp
ONBOOT=yes

If the device is configured for a static IP address, the interface configuration file looks similar to

Ethernet Interface Configuration File for Static IP
DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
NETWORK=192.168.1.0
NETMASK=255.255.255.0
IPADDR=192.168.1.15
USERCTL=no

If the ONBOOT option is set to yes, the device is activated at boot time using the network initialization script. Other device names include lo for the local loopback device, pppX for dialup interfaces, and irlanX for infrared devices where X is the device number starting with 0. Refer to the file /usr/share/doc/initscripts-/sysconfig.txt for additional options for
the files in this directory.

RELATED POSTS:-

Network Configuration

2009-09-18T19:05:00.000-07:00

If Ethernet card was present during installation, the installation program will allow you to configure the device.But this post deals with modification of configuration after installation. Even if you don’t need to modify the network settings, you can use this information to verify if the settings are correct.

NOTE:-
Because some servers do not have graphical desktops installed, we have consider the network configuration from the command line by modifying configuration files. If you have a graphical desktop and want to use a graphical application, go to the System menu on the top panel and select Administration, Network.

Network Configuration Files
The following configuration files exist for network configuration:

File	Use
. /etc/modprobe.conf file	This assigns a kernel module to each network device.
. /etc/sysconfig/network file	It Sets the hostname and check whether the networking is enabled.IPv6 is enabled or disabled.
. /etc/hosts files	Lists hosts and their IP addresses for hostnames that can’t be resolved by the DNS servers
. /etc/resolv.conf file	Sets the DNS servers (using their IP addresses)and the search domain. The values of the DNS servers are often tend to be added when the network is activated because the data can be provided by DHCP or a similar service.
. /etc/sysconfig/network-scripts/ directory	Contains scripts to start and stop a network device and a specialized configuration file for each device.
. /etc/rc.d/init.d/network file	Initialization script that starts and stops the network.

CAUTION:-
If the Graphical Network Configuration Tool from the Administration, Network menu item of the System menu has ever been run on the system, an /etc/sysconfig/ networking/ directory will exist. The files in this directory are only used by the graphical tool and are not by any of the network scripts. If changes are made to these files, they will not be applied to the actual network configuration files used.

Some of the network configuration files such as the ifup and ifdown scripts in /etc/ sysconfig/network-scripts/ does not need to be modified in most cases and should not be modified unless absolutely necessary. We are considering the network configuration files that may have to be modified to change the network settings and how to enable the changes.

Case-1 shows an example of a /etc/modprobe.conf file. The first line assigns the e100 kernel module to the eth0 network device. If the network card is supported, the module is automatically configured during installation or by Kudzu the first time the system is booted with the new card.

CASE-1
/etc/modprobe.conf
alias eth0 e100
alias scsi_hostadapter sata_sil
alias scsi_hostadapter1 ata_piix

The /etc/sysconfig/network file usually contains the content shown in CASE-2. If the NETWORKING option is set to yes, the networking subsystem is enabled but not necessarily started at boot time. The value of the HOSTNAME option is the hostname for the system. If it is not set, the default hostname is localhost. Refer to the file /usr/share/doc/ initscripts-/sysconfig.txt for additional options for this file.

CASE-2
/etc/sysconfig/network
NETWORKING=yes
HOSTNAME=smallville

Navigating the Filesystem

2009-09-18T05:44:00.000-07:00

By default, the prompt looks like the following:

[ankit@infinity ~]$

The first word before the @ symbol i.e "ankit" in this case is the username of the person currently logged in, and the word after the @ symbol is the hostname of the system. The part that follows the space after the hostname '~' is referred to as the current working directory. In this case, the ~ symbol means that the current working directory is the home directory of the user. When you start a terminal, the default directory is your home directory.

To change to a different directory, use the cd command. The can either be the full path to the directory or a directory relative to the current directory.

Notice that the shell prompt changes as you change directories. If you change to the documents/ directory, the prompt changes to the following:

[ankit@infinity documents]$

Notice that the prompt does not show where the current working directory is relative to the entire filesystem. It just shows the name of the current directory by itself.

To output the full path to the current working directory, execute the pwd command.

To create a directory, use the mkdir command. Again, the can be relative to the current directory or it can be the full path.

To remove a directory, invoke the rmdir command, where is a directory within the current directory or the full path to the directory. If any files are still in the directory , the error message Directory not empty will be displayed, and the directory will not be deleted. This prevents users from removing a directory that still contains files.To force the removal of a directory with all the files and subdirectories within that directory, use the rm -rf command. This command does not ask you to confirm the deletion, and there is no way to reverse the removal of the files and directories. Use extreme caution with this command. Double-check the directory specified before pressing Enter to execute the removal.

To remove a file, use the rm command. If only the filename is specified, it must be in the current working directory.

To view the contents of a current directory, execute the ls command, or use the ls command to view the contents of . As with the other commands discussed, can be relative to the current working directory or the full path to a directory. The ls command accepts the * wildcard character. For example, to list all the OpenOffice.org text documents, use the ls *.odt command, or the ls status* to find all files whose filename begins with status. Multiple wildcards can be used such as ls *status* to list all files that have status somewhere in their name.

To copy a file from one location to another, use the cp , where is the file to copy and is the directory or filename to copy it to.

When a file is moved, the file no longer exists in the original location. The mv command is similar to the cp command. The only difference is that the original file will no longer exist after the move operation. Multiple files can be specified as the for both the cp and mv commands, and both commands accept the * wildcard. For example, the mv *.txt textfiles/ command moves all files that end in .txt to the textfiles/ directory in the current working directory. Or, multiple files can be specified using their filenames.

Related Posts:-

About Shell Prompt

2009-09-16T20:30:00.000-07:00

Graphical environments for Linux have been introduced in the past few years. You can be perfectly productive in the X Window System and only have to open a shell prompt to complete a few tasks.

However, many Red Hat Enterprise Linux functions can be completed faster from the shell prompt than from a graphical user interface (GUI). In less time than it takes to open a file manager, locate a directory, and then create, delete, or modify files from a GUI, a task can be finished with just a few commands at a shell prompt. And even Linux is identified more as a character user interface rather than a graphical user interface and due to which its speed, efficiency and security increases much more than a any gui version.

A shell prompt looks similar to other command line interfaces with which you might be familiar. Users type commands at a shell prompt, the shell interprets these commands, and let the OS execute and work output accordingly. Experienced users can write shell scripts to expand their capabilities even further. It looks similar to the following

A Shell Prompt

Exploring Logical Volume Management

2009-09-07T05:04:00.000-07:00

The Logical Volume Management helps in the partition of your hard drives during the Red Hat Installation. Once the hard drives are partitioned there is no easy to expand the preallocated space.

Lets take a practical example, suppose you have set up the /home directory in a separate partition. You have planned and assumed that it will be enough for 10 users but now your company expands and suddenly, now you need space for 20 users. Now Without LVM , there is no easy way to expand the size of the /home partition. Now you need to back up the files of /home, find a partition with space, and than restore the files to that partition.

LVM allows you to reallocate chunks of disk space between different filesystem. So with LVM, if you have extra space in filesystem such as /var, you can reallocate that space to /home.

LVM volume group can be created at the installation time of Red Hat Linux.

Troubleshooting With FSCK

2009-09-03T00:27:00.000-07:00

Filesystems failure can be more troubling than problems booting Linux. There can be a sign of corrupted files, misaligned blocks, troubled configuration files, or even bad hardware.

Filesystem require troubleshooting during boot process. Linux may have trouble mounting a specific partition or check of filesystem integrity fails in some way. In either case, you will receive message fsck operation failed then you need root password to gain access to Linux.

The fsck command is important as is used by Linux periodically to automatically check most of partitions on system.

As with mkfs, it is a front end to commands dedicated to relevant filesystems such as fsck.ext2, fsck.ext3 and fsck.reiserfs. fsck command is all you need if you know filesystems format. If partition is formatted with ext3 , the fsck.ext3 command is called automatically.

fsck COMMAND SWITCHES

SWITCH	EXPLANATION
-a	Automatically repairs target filesystems without prompts. Should be used only within /etc/rc.sysinit
-b superblock	use a different superblock. Optional superblocks can be found via the dumpe2fs command.
-A	Check all filesystems listed in /etc/fstab.
-R	When -A is used, skip the root(/) directory filesystem.
-y	when fsck suggests a solution, it sets a default answer of "yes".

WARNING:- Do not run fsck on a mounted partition otherwise it can lead to severe filesystem damage.

If you suspect a problem, run fsck on unmounted partition, Generally default suggestions should be accepted to repair filesystem problems. It may lead to some data lost, but it will make your partition bootable again. Than you should be able to reboot Linux clearly.

Mounting Directories

2009-09-01T18:52:00.000-07:00

Before reading or writing to a Linux partition, you need to mount it. For this you need to specify the partition, directory being mounted, and the format associated with partition syntax for mount command is:-

#mount -t format partition directory

format          - Way the partition is configured such as ext2, ext3 or vfat.
partition   - hard drive being mounted such as /dev/sda1
directory /    - part of the Linux directory structure such as /boot, /home or /var
mount point

So now you could mount /home/mj directory on the /dev/sda1 partition which is formatted to ext3 filesystem as follows:-

# mount -t ext3 /dev/sda1 /home/mj

This is the proper mount format but in real application it can be simpler as with list in /etc/filesystems configuration file, mount command can look for this file format so all you need is

# mount /dev/sda1 /home/mj

TRICK:-
You can make it even more simpler by adding the following line to /etc/fstab configuration file

/dev/sda1 /home/mj ext3 defaults 1 2

So you now have to specify

#mount /dev/sda1
#mount /home/mj

TIP:-
Sometimes you need to unmount a directory. For example: Linux locks a CD Drive until you unmount the relevant directory with command as

# umount /mnt/cdrom

NOTE:- It is spelled as umount and not ~~unmount~~.

Tuning

2009-08-28T07:39:00.000-07:00

It is easy to convert an older partition formatted to the ext2 filesystem to ext3.

If you see the ext3 filesystem is virtually identical to ext2 with only difference that ext3 partitions include a journal. Which means if you create a journal for an ext2 filesystem, it automatically becomes an ext3 filesystem.

tune2fs -j command is used to convert partition from ext2 to ext3. For example, following command converts the /dev/hda1 partition from ext2 to ext3

# tune2fs -j /dev/hda1

Related posts:-

Formatting a partition

2009-08-28T07:24:00.000-07:00

Linux configures the mkfs command to format the Linux partitions. If a partition has previously formatted, you need to use mkfs command, and Linux will reformat the partition to same filesystem. Or you have have to specify the type of filesystem to be built by including the -t switch and for checking the bad blocks with -c switch before formatting.

For example; the following commands format the /dev/sda1 partitions to noted filesystems:

# mkfs -t ext2 /dev/sda1

# mkfs -t ext3 /dev/sda1
# mkfs -t vfat /dev/sda1
# mkfs -t reiserfs /dev/sda1

Or you can use:-
# mkfs -j /dev/sda1
(-j creates a journal with ext3 filesystem)

And if you are formatting a partition for Linux swap space, use the mkswap command. For example, if you want /dev/sda4 as a swap partition, the command is

# mkswap /dev/sda4

Related posts:-

Basic Linux Formats

2009-08-28T07:07:00.000-07:00

In Linux you can format a Filesystem in several different ways. The current default for Red Hat Linux is third extended Filesystem, ext3, there are other Filesystem available to use.

Linux is moving towards journaling filesystems. A journal records all pending changes, such as data to be written to disk. If a drive crashes, Linux can check the journal for pending changes. No disk check is required which can save a considerable amount of time.

FORMAT	DESCRIPTION
ext2	The second extended filesystem, which was standard earlier. If you have older system with ext2 partitions, they can easily be converted to ext3.
ext3	The third extended filesystem, which is current default for Red Hat Linux. Includes a journal, which records all pending changes, such as data to be written to disk.
reiserfs	The Reiser filesystem, which is based on different designs from Linux extended filersystem.
xfs	The Silicon Graphics Filesystem, which supports extremely large hard drives.

Several other Linux File System are available, including ext, bfs, minix, xia, and jfs. None of these are commonly used today.

RELATED POSTS:-

Installing and configuring Vmware2 to Run Linux (RHEL-5)

2009-08-22T09:05:00.000-07:00

ABOUT:-

Vmware server is a utility software that allows you to run a virtual server(O.S) over your host server. Like running a Linux server over Windows server or vice versa depending on your need. So that the virtual server can even share the resources of that single computer across multiple environments.Each virtual machine contains a complete system, eliminating potential conflicts. VMware virtualization works by inserting a thin layer of software directly on the computer hardware or on a host operating system.

Vmware is available as free download but its support and more advanced features are available with paid subscriptions. So simply download it from here. You need to register with them which is free obviously than you can download it.

This post is based on assumption that you want to install Linux on a windows platform so you need to download file based in .exe(executable) format. Simply install it once you have successfully installed it you will get an desktop icon similar to

Simply click on the above icon so that a browser is open similar to

Than enter your login name and password

This is the Home page of vmware that you see next. Select "Create a Virtual Machine" from right column

Than you get a screen same as below. The default name is VIRTUAL MACHINE which you can change to the name as desired in this case we taken name as RED HAT ES 5, Since we are installing rhel-5, you can choose any

Now you can see what all operating system you can install. Choose the Linux operating system and click next.

Now you have allocate the memory RAM to your virtual O.S so that whatever memory you specify here is used by the virtual machine to run your O.S. But remember whatever memory you alot in here is used by the virtual machine while it is running and your host server will not be able to use it while virtual machine is in use. So specify the memory accordingly so that both the operating system can be used in best possible way.

Choose "Create a New Virtual Disk" and click next.

Alot the Hard Disk (space) that will be used by the virtual server for storing all the data. Select "split disk into 2GB files" option and click next.

Select "Add a Network Adapter" and click next.

Select Network Connection as Bridged and select on yes and click next.

Select "Use a physical Drive" and click next.

Check the drive name in which you CD/DVD runs Select accordingly and click next.

Select "Don"t add a floppy Drive" and click next.

Select "Add a USB Controller" and click next.

Review all the information if you need to change something hit back or click on finish.

Than at starting page of vmware at the bottom you will see Create virtual machine task as Success which means you have successfully created a virtual machine.

At this point you have successfully created a virtual machine which is ready to install the Linux on it. Now depending upon the Linux distribution you can continue to install the Linux over this machine. We are installing RHEL-5 but you can nstall whichever distribution you prefer.

Now select the "VIRTUAL MACHINE" tab. It shows the currently installed virtual machine. In the right column select power on and see the task is successfully completed in bottom. Insert the installation Disks in the drive so that you see as

Click <ENTER>

Although testing CD is completely optional but we recommend you to check the cds before starting with installations. You can also choose "SKIP" to skip the checking of cd/dvd. After done click start or skip to continue.

Select Next to continue.

Select the desired language and click next.

Select the appropriate keyboard type and click next.

Since RHEL-5 is not free enter the installation Number which you have get while purchasing cd or from RED HAT. Enter the Number and click ok.

Select the appropriate partition type and select the check box below to review and modify the partition layout. Select it and than click Next.

After reviewing and modifying according click on next to continue.

Red hat uses the GRUB BOOTLOADER to install the Linux. Select and click on next.

Select manually and enter the desired host name and than click next.

Select the appropriate location on map shown with the help of mouse and click next.

The root is the primary user or administrator of Linux enter the desired password and click next.

Select the applications you required and select the customize now to manually select software's for installation and click next.

Select the desired software's and after selecting click next to continue.

Than it checks for dependies of the packages.

Click Next to continue.

Than it shows the cds that will be needed during the installations. click next to continue

Installations begins now. Enter the desired cds whenever prompted for it. After successful installations the virtual machine(only) reboots and Linux starts up.

Than you can simply work on it and once finished shutdown in Linux only the virtual machine automatically shut downs. You start and stop whenever required.

We have considered the basic installation and if you run in any problem in between or later leave a comment in the post we will try to return back to you.

Adding A New Hard Drive

2009-08-20T07:11:00.000-07:00

As a Linux Administrator, you need to know how to add new hard drives to your server, make sure your PC recognizes it, set and configure it. The basic hard drive configuration utility is fdisk. take a look at screenshot

The fdisk-1 command lists partition tables on local computer. In this case there are one IDE hard disks, designated /dev/hdc. The /dev/hdc hard drive includes a number of partitions.

If it shows that it does not have a valid partition than you need to do something about that. Use fdisk to open hard drive with following command:
# fdisk path

NOTE:- Depending the value of your PATH variable, you may need to specify the full path. If fdisk doesn"t work by itself, try /sbin/fdisk.
If there is a completely new hard drive, you"ll see a message showing " hard drive does not contain a valid partition table" but however if you dont see it, that means someone has already used it but in either case, next thing you"ll see is the fdisk utility prompt.

Command (m for help):

Now press m command to see the options available within the fdisk utility.

FDISK COMMANDS:-

COMMAND	RESULT
a	Sets or Unsets the bootable falg
d	Deletes a partition. You need to select the partition number.
l	Lists known partition types more than 100 different partitions are available.
m	Shows available fdisk commands.
n	Configures the new partition
p	Lists the current partition table.
q	Exits the fdisk without saving changes.
t	Allows to change the partition system ID. Partition number and ID of partition are needed.
v	Verifies current partition table.
w	Writes changes and exits from fdisk.

In fdisk utility, you need to create a new partition. Issue n command(see table). The utility lets you choose whether to create primary or extended partition. If there is already a extended partition, fdisk allows to create a logical partition.

Command (m for help) : n
Command action
e extended
p primary partition (1-4)

Start by creating a primary partition with p command. Make it primary partition and start with the first available cylinder. Specify size of partition in cylinders, KBs, or MBs.

Continue this till you have configured the desired space and allocated all space on hard drive. Once finished with configuring partitions, save your changes with w command. If there is some mistake or you want start again, exit without saving by using the q command.

Before you can use the new partition, you need to format it to a system such as ext2, ext3, or VFAT.

Managing partitions with fdisk

2009-08-17T07:40:00.000-07:00

The fdisk utility is traditional for managing partitions and is fuctionally similar to the MS-DOS tool of same name but looks different and is much more versatile. It can help to manage the empty space on existing drive, lets you configure up to 4 primary on a hard drive, It can be use to change the type of partition to one over 100 different types, including FAT32, Novell NetWare, Linux Logical Volume Manager, Linux Swap and of course a standard Linux partition.

Managing Partitions

2009-08-14T22:13:00.000-07:00

The partition of a Drive actually means to organize the hard drive into sections, which can then be formatted separately. Every Hard Drive requires atleast one partition. Maximum partitions can upto 16 depending upon type of drive.

The different types of partitions on a Hard Drive are:-

1. Primary Partition:-
    Upto four primary partitions can be created on IDE or a SCSI hard drive.One primary partitions must be active; it should include a bootloader such as GRUB or the Linux Loader (LILO).

2. Extended Partition:-
    A primary partition can be converted into an extended partition which can further be subdivided into logical partitions depending upon your requirements.

3. Logical partitions:-
    An extended partition can be subdivided into logical partitions and there can be upto 11 logical partitions on a SCSI hard drive or upto 12 logical partitions on an IDE hard drive.

In Red Hat Linux installation process Disk Druid can be used to create different partitions but however it is available only during installation once installed you can only use fdisk utility.

Partition Schemes

2009-08-13T11:36:00.000-07:00

Linux provides a variety of ways to set up partitions but there are a few standard partition schemes also.. By default, while installing Red hat Linux, you will set up at least two directories on separate partitions; the root (/) directory and /boot. The /boot directory is commonly mounted on its own partitions because many Linux installations cannot start if the files in the /boot directory are stored above hard drive.

Installations carried over servers involve several more mounted directories /home, /usr, /var.

MOUNTED DIRECTORIES	COMMENT
/,swap	Typical configuration with one small hard drive.
/,/boot/,swap	Typical configuration with large hard drive. This is default configuration for RED HAT LINUX Personal Desktop and Workstation installation
/,/boot,/var,swap	Possible configuration where log size, such as from a web server, is an issue. This can prevent runaway log files from crowding all free space.
/,/boot,/home,swap	Possible configuration for a Linux Server with home directories for a number of other users. With other measures such as quotas, it can regulate space usage by users.

Basic Linux Directory Structure

2009-08-12T08:26:00.000-07:00

Red Hat Linux organizes files into directories according to the Filesystem Hierarchy Standard(FHS):

/
The Top level root directory. All other directories are below root directory or they are the subdirectories of root directory. Any directory not mounted in a separate partition is automatically part of root directory volume.

/bin
Contains basic command line utilities. It should not be configure in a separate partition, but if you do than you will not be able to access utilities in rescue mode.

/boot
Includes command and files required for boot purpose such as Grand Unified Bootloader(GRUB), Initrial Ram disk, Linux Kernel. It is good idea to mount /boot in a separate partition.

/dev
Lists available device drivers. For example; if floppy drive is mounted, it might be mount /dev/fd0 on a directory such as /mnt/floppy.

/etc
Contains basic Linux configuration files, including files related to passwords, daemons such as Apache and Samba, and the X window.

/home
Includes home directories for all but the root is the user. Mounting this directory in separate partitions, requires leaving enough space for users to add files.

/initrd
Configures an empty directory used by the Initial RAM disk during the boot process. This is directory is required for boot purposes by Linux, if you delete this directory Linux will not boot, you"ll get a Kernel panic message.

/lib
Lists program libraries needed by a number of different applications as well as Linux Kernel.

/lost+found
Contains orphaned files. Utilities such as fsck places empty unidentifiable files in this directory.

/misc
Notes a common mount point for shared NFS directories.

/mnt
Contains mount point of removable media such as floppy (/mnt/floppy), CD-ROM(/mnt/cdrom) and Zip (/mnt/zip) drives.

/proc
Kernel related processes that are currently running are included in it and along with it some of the files in this directory list the current resource allocation such as /proc/interrupts lists currently allocated (IRQ) ports.

/root
The home directory of the root user. /root directory is a subdirectory of the root (/) directory.

/sbin
Contains the system administration commands.

/tftpboot
It supports the diskless workstations popularly known as remote terminals.

/tmp
Serves as a dedicated storage locations for temporary files; also considered good place to download the files. by default, the /etc/cron.daily/tmpwatch script removes the files older than 10 days from this directory.

/usr
Includes programs and data available to all the users. For example; the perograms associated with the OpenOffice suite are installed in /usr/bin

/var
Contains the variable data , including the log files and print spools. This directory is separately mounted.

/opt
Includes standard location of third party softwares such as Sun Star Office or Corel Word Perfect.

Related posts:-

Understanding Filesystem Hierarchy Standard

Ownership

2009-08-10T05:44:00.000-07:00

This post confirms my ownership of the site and that this site adheres to Google AdSense program policies and Terms and Conditions.

Understanding Filesystem Hierarchy Standard

2009-08-09T03:22:00.000-07:00

Everything in Linux is configured as a File. Directories, hardware device drivers and partition all are represented by files. The organizational system for Linux Files is known as FILESYSTEM HIERARCHY STANDARD (FHS).

While installing Linux you can mount all Linux directories on single partition or separate partitions. Establishing separate partitions Limits risk to system. For example; web servers such as APACHE can consume gigabyte of space, crowding your free space. Users will no longer be able to save files, There would be no space to prepare print jobs, and chaos would undoubtedly result. However mounting right directory in separate partitions, users can still work and save files even if the partitions with log files become full.

RELATED POSTS:-

Other Text editor

2009-07-30T08:52:00.000-07:00

vi is not the only text editor available with Linux. There are 3 other major text editors;

emacs
pico
joe

By default none of the above 3 are included in Red Hat Linux.

1. emacs:-
The emacs is one of the most popular text editor in world of Linux/Unix. Once emacs RPM is installed, any text file can be open with its help. For eg:- To open /etc/inittab in emacs use

# emacs /etc/inittab

Note:- RPM stands for Red Hat Package Manager, the standard way Red Hat organizes package.

2. pico:-
pico is another popular Linux/ Unix editor, which is installed as part of the pine e-mail RPM package. Once installed it can be used to open text files. For eg:- to pen /etc/inittab in pico use;

# pico /etc/inittab

Opening pico in a Gui brings a control character driven interface. For example, the EXIT command is shown as ^X which can be run by Ctrl+x command.

3. joe:-
joe is another popular editor also known as " Joe's own editor". Once installed can be used to open text files.

#joe /etc/inittab

It also opens character driven interface like pico. But Unfortunately, F1 key not bring help but instead Ctrk+k command is required for same.

Related posts:-

Basic VI commands

2009-07-11T23:15:00.000-07:00

The most commonly used commands in vi Editor are as follows:

COMMAND	DESCRIPTION
a	starts insert mode after current position of cursor.
A	starts insert mode at end of the current line.
cw	Deletes the current word and than enters the insert mode to replace that word.
dw	Deletes the current word without entering the insert mode.
dd	Deletes the current line.
G	Moves cursor at the end of the line.
15G	Moves cursor to fifteenth line.
h	Moves cursor left one space.
I	Enters insert mode.
o	enters insert mode opening line below current cursor.
O	enters insert mode opening line above current cursor.
:q	Exits from vi.
r	Replace; replaces current character with next character.
:set nu	shows line number for the current line
u	Undoes the last change
:w	Writes the current file.
Esc	Escapes from insert mode
/system	Searches the word System in current file

Using the vi Editor On Linux

2009-07-04T22:18:00.000-07:00

Linux relies on large number of text files for configuration. So, you need a text editor to configure Linux. vi is one of the most commonly used text editor.

It is easy to open a file with vi. For eg:- If you need to open /etc/inittab file, use

# vi /etc/inittab

There are three basic ways to work in vi

Command mode is default
Insert mode is to insert text.
Execute mode to run regular shell commands

Command Mode:-
When you open a file in vi, first or default mode is command mode. It can be used to scroll through text, search for different text strings delete specific characters, words or lines. One aid in vi is line numbers, which can be activated as

:set nu

1. open terminal and type
# vi /etc/inittab

2. vi opens inittab file as follows

3.Now to see the line number type :set nu

4.you get

vi allow you to use the directional keys on keyboard (arrows, page up, page down). If you know the line number you want, the G command can help you. When used with line number, such as 20G, it takes you to desired line.

DELETING TEXT:-
There are three commands associated with the current location of the cursor:

x : Deletes the current character

dw : Deletes the current word
dd : Deletes the current line

If you accidentally deletes something, than U command reverses the last command entered.

SEARCHING FOR TEXT:
Just start with a forward slash ( / ) followed by the word. For example;

/proceed
Cursor highlights the first place where the "proceed" is found in the file.

INSERT MODE:-
It is used to insert the text into a file. These are several ways to do this as follows:

COMMAND	ACTION	COMMENT
i	Insert	Everything type is inserted, at current position of cursor
a	Append	Everything type is inserted, starting one character after current cursor position.
A	Same as a	Closely related to a, where everything is inserted, starting at the end of the line with cursor.
o	Open	Everything type is inserted, starting one line below current position of the cursor. If "O" is used it insert , it starts one line above current position of cursor.

Execute Mode:-
Regular shell commands can be run from inside the vi editor. Just type " :! " followed by the command.

For example;
If you are creating a cript, you will need to know the directory location of a certain file. You list the files in /etc/cron.daily directory as:-

:!ls /etc/cron.daily

Regular execute mode starts with colon ( : )
File management are associated with execute mode, including :q(to exit a file) and :w(to write current text to file)
If you think there is some problem in text you inserted, exit from vi without saving any changes, use the :q command.

Related posts:-

Command Combinations

2009-07-02T04:38:00.000-07:00

Sometimes it is required to use more than one command in a line or simultaneously. For example:-

If you are using find command and result has a large number of files you can use grep command to search your desired file.

Let"s say we want to find .html files on our system. So we use

# find / -name *.html

It may show you hundreds of file flashing past you on your terminal screen. An alternative is

# find / -name *.html | grep bookmark

This command searches through result for text string "bookmark". Only those files with both strings are outpuut to the screen.

Similarly we can have

# who" grep mj
# ps aux " grep mozilla

The first command who, lists all users currently logged on Linux system. when you pipe(") the result to the grep mj command, you"ll find no. of times that user mj is currently logged on the system.

The second command, ps , lists the process currently running on Linux system. Three switches, aux(a dash is not required ps command switches) , leads very long lists of processes run by all users (a), each associated with username(u) , independent of virtual terminal(x). you need grep to search through these processes. This combined command returns all processes with the word mozilla.

Related Posts:-

Manipulating Files

2009-06-25T22:54:00.000-07:00

Several commands are available that allow you to learn about and search for and through different files.

1. wc
The wc command is used to count the lines, words, and character in any text file.

# wc filename
1914 9298 76066

These numbers corresponds to the number of lines, words and character in the text file.

COMMAND	RESULT
wc -l filename	Number of lines in the file
wc -w filename	Number of words in the file
wc -c filename	Number of characters in the file

2.find
The find command is used to find the file through directories and subdirectories. For eg; if you want the file named fig06.tif, you use the following command:

# find / -name fig06.tif

This command searches in the root directory and all the subdirectories for the fig06.tif file.

With the find command, you can also use the wildcards such as the asterisk(*) and question mark(?), in your search term.

3. locate and slocate
An alternative to the find command is the locate command. This command searches through the database of files. In Red Hat Linux, the locate command is actually soft-linked to more secure slocate command. The database is update per the /etc/cron.daily/slocate.cron script.
take a look at the default command at that script:-

/usr/bin/updatedb -f "nfs,smbfs,ncpfs,proc,devpts" \
-e "/tmp,/var/tmp,/usr/tmp,/aft,/net"

as we can see from the updatedb man page, the -f switch excludes a number of filesystem types, and -e switch excludes a number of directories that should be accessible to the root user.

Once database is located; it is more flexible; for example, if you use the following command it returns all the files that include the text string fig0:

# locate fig0

The locate command works as if the asterisks are assumed before and after the search terms.

4. grep
grep command is a easy way to search through a file. As a system administrator, you may have long lists of the users. If you want to search through your /etc/passwd file for a user named michael jang, try following command:

# grep "michael jang" /etc/passwd
mj:x:500:500:michael jang:/home/mj:/bin/bash

The response tells that there is a user named michael jang. It also includes the home directory and default shell for that user.
you can even use grep to search through a series of files with commands like:

# grep mj *
# grep -c bash /etc/passwd

The first command looks for string mj in all files in current directory.
The second command, counts the number of lines that include the word bash.

Related Posts:-

Managing Files

2009-06-21T20:52:00.000-07:00

Linux includes a number of commands to help you read files in different ways. You can read files from top to bottom or vice-versa, you can be limited to few lines, you can count the lines, words, alphanumeric characters within a file, In addition linux lets you search through the files.

1. file
Although some distribution differentiate between file types by colour, but there are no standard extensions in Linux. Executable files don"t end in .exe similarly for documents file may not end in .doc . The file command lets you view type of each file.

2. cat
The concatenate(cat) command is used to read a file in linux. It sends the text of a file to standard output.

# cat file

It can even be used to read the multiple files, in sequence, with the
cat file1 file2 command

3. head and tail
The head file provides you with the view of the first few lines of the file; while the tail command provides you with the view of the last few lines of the same file. You can regulate the amount of the file that you see with switches. For eg:-

# head -n15 abc.txt
It provides you with the first 15 lines of abc.txt file similarly if you substitute head with tail it provides you with the last 15 lines of abc.txt file.

COMMAND	RESULT
head 400b abc.txt	it shows the first 400 bytes of the file abc.txt
tail 4k abc.txt	it shows final 4kb of the file known as abc.txt
head 3m abc.txt	it shows first 3mb of the file abc.txt
tail -n22	it shows last 22lines of abc.txt

Note:- head command is generally used when you want to know what actually the file is about which can be interpreted by knowing first few lines but what the tail command is used you guess it and provide it in comments section than i will let you know.

4. more and less
The more and less commands used to view the contents of a text file.
The more command is to review the contents of the file one page at a time.
The less command is more versatile; unlike more, it allows you to scroll up and down any large file by using page up and down keys.

Because they can read text a little bit at a time, these commands can open file more quickly than text editor like vi.

# less -N bigfile

Related Posts:-

Setting up Files And Directories

2009-06-13T03:37:00.000-07:00

Linux includes specific commands for creating and deleting directories, file management and so on:-

1. touch:-
touch command is simply used for creating a new file in Linux. It creates an empty file under the current directory. For eg:-

# touch filename

2. cp
the cp command is used to copy the contents from source to destination. For eg:-

# cp file1 file2
It simply copies the content of file1 to file2. cp command can be used as shown in table

Command	Result
cp file1 file2	copies the content of file1 to file2. The destination file has new creation date and inode number.
cp file Dir1*	copies multiple files to directory
cp -f file1 file2	if file named with file2 already exists, than it overwrites its content without prompting.
cp -i file1 file2	if file named with file2 already exists, this command prompts confirmation before it overwrites its contents.
cp -p file1 file2	copies content of file1 to file2. The destination file has the same creation date and inode number as the source file
cp -r Dir1 Dir2	copies contents of directory1 to directory2. The effect is recursive; i.e if there are subdirectories under the Dir1, there files and directories are also copied.
cp -u file1 file2	If you already have file named file2 and file1 is newer, this command overwrites its contents without prompting.

Note:- An inode is the identifier used on each Linux partition for a file. Every file gets its own inode. The inode includes metadata about the file, which includes the permissions, size, last access time, and its disk block were it is located. If inode is misaligned or corrupted it won"t be able to find the associated file. In addition, identical files have the same inode number.

3. mv
mv stands for move and if you want to rename a file in the linux you move it. The mv command changes the name of the file.

Command	Result
mv file1 file2	changes the name of a file from file1 to file2.
mv file Dir1*	Moves multiple files to the directory.
mv -i file1 file2	if file named file2 already exists, this command prompts you for confirmation before overwriting this file.
mv -f file1 file2	if a file named file2 already exists, this command overwrites its contents without prompting.

4. rm
rm is used to remove files and directories. This is one reason that Linux Administrators are not advised to run Linux in root or superuser mode, because small mistakes in this command can easily remove all your Linux files.lets take an example

suppose you want to remove a group of temporary directories in your root(/) directory: a.tmp, b.tmp, c.tmp. You want to use rm -r *.tmp command, but instead you type the following:

#rm -r * .tmp

Because there is space between the * and .tmp, the shell assumes that you want to recursively delete all directories and then delete the file name .tmp. And surely you don"t want to delete all your directories and corresponding files and data.

For this reason, Red Hat configures the following as an allias for the root user:

alias rm=" rm -i "

the alias ensures that whenever you want to use the rm command (even rm -r), the shell prompts you for confirmation before you delete any other file.

TIP:- you can find default aliases with the alias command

rm file 1	Deletes file1 without prompting for confirmation.
rm -d Dir1	Deletes Dir1 without prompting for confirmation.
rm -i file1	Deletes file1 after prompting for confirmation from the user
rm -f file2	If a file name file2 already exists, this command overwrites its contents without prompting.
rm -r *	Removes file recursively, if there are any subdirectories in the current directory, this commands deletes them(and all their files) as well

5. ln
In Linux instead of just copying or moving a file, you can link it. Links are common, especially for those programs which run at different runlevels. While you link a file, you are actually creating another path to a currently existing file. Lets take an example

Suppose you and your friend or colleague are working on a file named project, you can create a linked file in your home directory. assume project file is in /home/jm directory. To create link use following command:

#ln /home/jm/project /home/mj/project

When you work on either file, the change and results are visible and accessible to those who access both the directories. This sometimes known as hard link.

Note:- The ln file1 file2 commands produces the same result as cp -p file1 file2

Another useful option for links is symbolic mode which allows you to see the linked file.

# ln -s /home/jm/project /home/mj/projectyou will see the linked file when you run a long listing (ls -l) of that file. This is known as a soft link.

6.mkdir
mkdir command is used to create directories. The directory that you create does not have to be based in your current directory for this you have to specify the path. You can also assign permission to the directory.

# mkdir -p Dir1/Dir2
Creates a directory named Dir2. Id Dir1 does not exist, the -p switch tells Linux to create that directory as well. Since path is not specified so both are created as subdirectories of the current directory.

# mkdir -m 755 /usr/Dir3
Creates a directory named Dir3 as a subdirectory in the /usr directory(here the path is specified). The permissions(755) are rwx for the owner and r-x for other members of the group of group and everyone else.

7. rmdir
This commands allows you to delete empty directories.

# rmdir -p Dir1/Dir3
This command deletes Dir3 if it is empty. If the only "file" in directory Dir1 is Dir3, this command also deletes directory Dir1.

Starting at the command line

2009-06-11T20:19:00.000-07:00

Although the linux is provided with number of integrated GUI tools, still the best way to control the linux is command line interface. Command line tools have more options than the GUI tools. Theyv are even faster than GUI.

Presently we are considering the commands working on Bourne Again Shell(bash). Commands are capable of creating, editing, deleting, navigating to directories and files and almost any part of the system can controlled with the help of the commmand line.

Considering the various commands available are:-

* pwd
It stands for "present working directory" and it tells the absolute path of your current directory.
for example
# pwd
/etc/httpd/conf the output tells you are currently in the /etc/httpd/conf

*cd
cd is used for change directory command.

cd..	moves up one directory level
cd../..	moves up two directory level
cd /home/mj	navigates to the home directory of user mj
cd ~	Navigates to your home directory. works for any user

Note:- Linux is case sensitive so remember all the small letters in commands represents the lower case letters.

ls:-
ls is a versatile command which is used to list all the directories and files under your current directory. It can be used to find permissions, size of a file, check ownership, differentiate b/w file types.

Command	Result
ls	lists in alphabetical order all the non-hidden files in current directory
ls -a	list all the files including the hidden files
ls -r	lists in reverse alphabetical order all non-hidden files in current directory
ls -F	Lists all files by type. The character at the end of each file indicates the file type.
ls -i	Lists the files by inode numbers. An inode number represents the location of the file on a volume.
ls -l	Lists all the files in current directory, including the current directory(.) and the parent directory(..). Also lists the size, owner, and permissions associated with each file in what is known as long listing format.
ls -t	lists the files by the last time they were changed
ls -u	lists the files by the last time they were accessed

Path Management:-
While describing the location of a file, either specify the absolute path or relative path. An absolute path describes the location of a file relative to the root(/) directory. For example, following command get to the scripts that start a number of Linux daemons

# cd /etc/rc.d/init.d
forward slash in front makes it a absolute path. this command can be started from anywhere in the Linux to get to this directory.

absolute and relative paths apply to the commands as well. eg:-
# ls /etc/rc.d/init.d

However if you use the relative path, your current directory matters. eg:- if the output from the pwd command is /home/mj, the following command won"t work unless you have an /home/mj/etc/rc.d/init.d directory:-

# ls /etc/rc.d/init.d

Using the Red Hat Package Manager

2009-04-17T20:51:00.000-07:00

The Red Hat Package Manager’s primary function is to allow the installation and removal of files (typically precompiled software). It is easy to use, and several graphical interfaces have been built around it to make it even easier. Red Hat, Mandrake, and other distributions use this tool to distribute their software. In fact, almost all of the software mentioned in this book is available in RPM form. The reason for going through the process of compiling software yourself in other modules is that you can use compile-time options that are not available in an RPM. Basically, an RPM file is a collection of all the files necessary for a particular program to
run. It also includes descriptions of the program, version information, and the necessary scripts to perform the installation itself.

NOTE
In this context, I am assuming that the RPM files contain precompiled binaries. Several groups, such as Red Hat, also make source code available as an RPM, but it is uncommon to download and compile source code in this fashion.

The RPM tool performs general management of all of the RPM packages that are installed on a given host. This includes tracking which packages are installed, their version numbers, and their file locations. All of this information is kept in a simple database file on the host.

In general, software that comes in the form of an RPM is less work to install and maintain than software that needs to be compiled. The trade-off is that by using an RPM, you accept the default parameters supplied in the RPM. In most cases, these defaults are acceptable. However, if you need to be more intimately aware of what is going on with a service, you may find that compiling the source yourself will prove more educational about what package components exist and how they work together. But assuming that all you want to do is install a simple package, RPM is perfect. There are several great resources for RPM packages, including the following:

● http://www.rpmfind.net
● http://www.freshrpms.net
● http://www.linuxapps.com
● ftp://ftp.redhat.com/pub/contrib

Of course, if you are interested in more details about RPM itself, you can visit the RPM web site at http://www.rpm.org. RPM comes with Red Hat Linux (and derivatives) as well as Caldera Linux. If you aren’t sure if RPM comes with a particular distribution, check with your vendor.

NOTE
Although the name of the package manager says “Red Hat,” the software can be used
with other distributions as well. In fact, RPM has even been ported to other operating
systems, such as Solaris and IRIX! The source code to RPM is open-source software, so
anyone can take the initiative to make the system work for them.

Determining a Server’s Functions

2009-03-13T22:22:00.000-07:00

Before installing the Linux server, it can be useful to plan and determine exactly as to what purpose the server will serve. Even if you do not know all the functions available, it can give you an idea as to what is or isn’t required of the server you plan to install. A strategic planning ensure that the system has all the software it needs, and that it isn’t slowed down or made exploitable by having unnecessary software installed.

Step by Step
1. Consider each of the following questions, by making a list of services that are definitely needed or definitely not needed:

● Will this system’s disk resources will be accessible for mounting by other systems using NFS? Will it provide print services?

● Which Internet-related services will this server provide? For example, will it be used as a web server? Will it provide mail, IRC, newsgroup, or other such services?

● Will the system be a database server?

● Will the system perform authentication tasks such as running as an LDAP or NIS server?

● Will the system perform any network functions by performing routing, firewalling, SNMP or traffic monitoring, or the like?

● Will program development take place on this system? Which languages will be used? What compilers, debuggers, libraries, and utilities are necessary?

● How will remote users access the system? Do they need FTP or telnet access? Will SSH or rlogin or rsh be used?

● Will the system be accessible from the console, and if so, is the X Window System necessary? How much work will be done in the GUI, and which windowing environments are required?

2. Looking at the list of requirements, make a note of any components that are implied by the must-have items. For example, a web and database server may require tools to interface from the web pages to the database, so Perl or PHP might be useful.

3. What documentation needs to be installed on this system? If it will be a developer or end-user resource, there may be more documentation requirements than if it will be just one of many systems in a large server farm.

4. If this is a test server, what type of functions would you like to try? Make a note of each, and when it comes time to install the software, you may be able to find packages you didn’t know existed.

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Methods of Installation

2009-03-13T05:50:00.000-07:00

As the connectivity and speed of both local area networks and Internet connections have increased a lot, so it is becoming an increasingly popular option to perform installations over the network rather than using a local CD-ROM.

In general, you’ll find that network installations becomes rather important once you’ve decided to install Linux over many machines and therefore requires a fast installation procedure in which many systems can be installed at the same time.

usually, server installations aren’t well suited to automation, because each server usually has a unique task to perform; thus, each server will have a slightly different configuration. For example, a server dedicated to handling logging information sent to it over the network is going to have especially large partitions set up for the appropriate logging directories, compared with a file server that performs no logging of its own.

Because of this, you might focus exclusively on the technique for installing a system from a CD-ROM. Of course, once you have gone through the process from a CD-ROM, you will find performing the network-based installations to be very straightforward.

If It Just Won’t Work Right . . .
Suppose you’ve gone through the installation procedure . . . twice. We said it should work. The installation manual said it should work. The Linux guru you spoke with last week in online forums said it should work.

But it’s just not working.

No operating system installs smoothly 100 percent of the time. (Yes, not even the Mac OS!) Hardware doesn’t always work as advertised, combinations of hardware conflict with each other, the CD-ROM might have CRC errors on i.

With Linux, you have several paths you can follow for help. If you have purchased your copy from a commercial vendor such as SuSE or Red Hat, you can always call tech support and reach a knowledgeable person who is dedicated to working through the problem with you. If you didn’t purchase a box set, you can purchase support from Red Hat and other distributors of Linux. Last, but certainly not least, is the option of going online for help. An incredible number of web sites like this are available to help you get started. They contain not only useful tips and tricks but also documentation and discussion forums where you can post your questions. Obviously, you’ll want to start with the site dedicated to your distribution: www.redhat.com for Red Hat Linux. Other distributions have their own sites.

Here are some recommended sites for installation help:
● comp.os.linux.admin
This is a newsgroup, not a web site. You can read it with a news client, or through the web at http://groups.google.com.

● comp.os.linux.redhat
this is another newsgroup, but Red Hat Linux–specific.

● linux.redhat
This is another Red Hat Linux newsgroup.

● http://www.linuxdoc.org/
This site is a collection of wonderful information about all sorts of Linux-related topics, including installation guides. Just a warning, though: Not all documents are up to date. Be sure to check the date of any document’s last update before following the directions. There is a mix of cookbook-style help guides as well as guides that give more complete explanations of what is going on.

● http://linuxnewbie.org/
This site features “Newbie-ized Help Files” that help with a variety of hardware and software issues.

And last but not the least share your problem with us we would surely try to find one or other way to your problem. There are many online forum for your support, infact you will always have such a large support for free with LINUX only.

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Dual-Booting Issues

2009-03-12T20:40:00.000-07:00

If you are new to Linux, you may not be ready to commit to a complete system with Linux when you just
want a test drive. All distributions of Linux can be installed on only certain partitions of your hard disk while leaving others alone. Typically, this means allowing Microsoft Windows to coexist with Linux. So you can install Linux and Microsoft windows on same machine without any problem between the two.

Because we are focusing on server installations, this post will not cover the details of building a dual-booting system; however, anyone with a little experience in creating partitions on a disk should be able to figure this out. But anyways i will be including this in my later posts. If you are having difficulty, you may want to refer
to the installation guide that comes with your distribution.

Some quick hints:

If a Windows 95 or Windows 98 partition currently consumes an entirehard disk as drive C:, you can use the fips tool to repartition the disk. Simply defragment andthen run fips.exe.

If you are using Windows NT/2000 with NTFS and have already allocated all the disk with data on each partition, you may have to move data around a bit by hand to free up a partition.

Don’t bother trying to shrink an NTFS partition, though; because of its complexity, it doesn’t like being resized, and doing so will lead to corruption.

NOTE:-

From the perspective of flexibility, NTFS doesn’t sound like a good thing, but in reality it is. If you have to run a Windows server, use NTFS.

You may find using a commercial tool such as Partition Magic to be especially helpful, because it offers support for NTFS, FAT32, and regular FAT, as well as a large number of other file system types. Its user interface is also significantly nicer than fips.

If you’re going to be installing a dual-boot system, install Linux last. If you install Windows last, it will clobber the boot information for your Linux system. If you install Linux last, it will recognize that you have Windows installed and let you choose which one you want to boot by default.

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Uptime

2009-03-12T03:43:00.000-07:00

All of these points about taking care of your servers and making sure silly things don’t cause them to crash from a long-time UNIX philosophy: Uptime is good. More uptime is better.

The UNIX (Linux) uptime command tells the user how long the system has been running since its last boot, how many users are currently logged in, and how much load the system is experiencing. The last two are useful measures that are necessary for day-to-day system health and long-term planning. (For example, the server load has been staying high lately, so may be it’s time to buy a faster/bigger/better server.)

But the all-important number is how long the server has been running since its last reboot. Long uptimes are a sign of proper care, maintenance, and, from a practical standpoint, system stability. You’ll often find UNIX administrators boasting about their server’s uptimes the way you hear car buffs boast about horsepower. This is also why you’ll hear UNIX administrators cursing at system changes (regardless of operating system) that require a reboot to take effect, even though applying the latest kernel security patch may justify that reboot. You may deny caring about it now, but in six months you’ll probably scream at anyone who reboots the system unnecessarily. Don’t bother trying to explain this phenomenon to a nonadmin, because they’ll just look at you oddly. You’ll just know in your heart that your uptime is better than theirs.

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Server Design

2009-03-12T03:34:00.000-07:00

When a system becomes a server, its stability, availability, and performance become a significant issue. These three factors are usually improved through the purchase of more hardware, which is unfortunate. It’s a shame to pay thousands of dollars extra to get a system capable of achieving in all three areas when you could have extracted the desired level of performance out of existing hardware with a little tuning. With Linux, this is not hard. Even better, the gains are outstanding!

The most significant design decision you must make when managing a server configuration is not technical but administrative. You must design a server to be unfriendly to casual users. This means no cute multimedia tools, no sound card support, and no fancy web browsers (when at all possible). In fact, it should be a rule that casual use of a server is strictly prohibited— not only to site users but site administrators as well.

Another important aspect of designing a server is making sure that it has a good environment. As a system administrator, you must ensure the physical safety of your servers by keeping them in a separate room under lock and key (or the equivalent). The only access to the servers for nonadministrative personnel should be through the network. The server room itself should be well ventilated and kept cool. The wrong environment is an accident waiting to happen. Systems that overheat and nosy users who think they know how to fix problems can be as great a danger to server stability as bad software (arguably even more so).

Once the system is in a safe place, installing battery backup is also crucial. Backup power serves two key purposes: to keep the system running during a power failure so that it may gracefully shut down, thereby avoiding file damage or loss; and to ensure that voltage spikes, drops, and other noises don’t interfere with the health of your system.

Here are some specific things you can do to improve your server situation:
● Take advantage of the fact that the graphical user interface is uncoupled from the core operating system, and avoid starting the XWindow System (Linux’s GUI) unless someone needs to sit at the console and run an application. After all, like any other application, X requires memory and CPU time to work, both of which are better off going to the server processes instead.

● Determine what functions the server is to perform, and disable all other functions. Not only are unused functions a waste of memory and CPU, they complicate the process of securing the server.

● Unlike some other operating systems, Linux allows you to pick and choose the features you want in the kernel. The default kernel will already be reasonably well tuned, so you won’t have to worry about it; but if you do need to change a feature or upgrade the kernel, be picky about what you add and what you don’t. Make sure you really need a feature before adding it.

NOTE:-
You may hear an old recommendation that you recompile your kernel to make the most effective use of your system resources. This is no longer true—the only reason to recompile your kernel is to upgrade or add support for a new device. Remember: Once a server is in use, don’t change what’s stable and performs reasonably well without a good reason.

Using Tools to Monitor Security

2009-03-10T21:50:00.000-07:00

Crackers — are people who, for purposes or to amuse themselves, like to break into other people’s computers — to steal information-are a clever bunch. If there is any vulnerability in a system, they will find it. Fortunately, the Linux development community is quick to find potential exploits and to find ways of slamming shut the door before crackers can enter. Fortunately, too, Red Hat is diligent in making available new, patched versions of packages in which potential exploits have been found. So your first and best security tool is making sure that whenever a security advisory is issued, you download and install the repaired package. This line of defense can be annoying, but it is nothing compared to rebuilding a compromised system.

And as good as the bug trackers are, sometimes their job is reactive. Preventing the use of your machine for bad purposes and guarding against intrusion are, in the end, your responsibility alone. Again, Red Hat Linux equips you with tools to detect and deal with unauthorized access of many kinds. In later posts, you’ll learn how to install and configure these tools and how to make sense of the warnings they provide. If your machine is connected to the Internet, you will be amazed at the number of attempts that are made to break into your machine.

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Configuring a Secure System

2009-03-10T21:35:00.000-07:00

Linux Administrator"s most important duty is the , security of the computer and data integrity.

What does this mean? The system administrator’s most important task, first and foremost, is to make certain that no data on the machine or network are likely to become corrupted, whether by hardware or power failure, by misconfiguration, or by malicious or inadvertent intrusion from elsewhere.

Everyone involved in computing are aware of the increasing serious attacks upon machines connected to the Internet. The majority of these have not targeted Linux systems, but that doesn’t mean that Linux systems
have been entirely immune, either to direct attack or to the effects of attacks on machines running other operating systems.

In one such Distributed Denial of Service (DDoS) attack aimed at several major online companies, many of the “zombie” machines(Machines unknowingly used to spread malware without its owners consent ) — so that the vandals could employ thousands of machines instead of just a few — were running Linux that had not been patched to guard against a well-known security flaw. In the various “Code Red” attacks of the summer of 2001, Linux machines themselves were invulnerable, but the huge amount of traffic generated by this “worm” infection nevertheless prevented many Linux machines from getting much Web-based work done for several weeks, so fierce was the storm raging across the Internet. While these infection did not corrupt Linux machines as it did those running a different operating system.

Security can be as simple as turning off unneeded services, monitoring the Red Hat Linux security mailing list to make sure that all security advisories are followed, and otherwise engaging in good computing practices to make sure the system runs robustly. Or it can be an almost full-time job involving levels of security permissions within the system and systems to which it is connected, elaborate firewalling to protect not just Linux machines but machines that, through their use of non-Linux software, are far more vulnerable, and physical security — making sure no one steals the machine itself! For any machine that is connected to any other machine, security means hardening against attack and making certain that no one is using your machine as a platform for launching attacks against others. If you are running Web, ftp, or mail servers, it means giving access to those who are entitled to it while locking out everyone else. It means making sure that passwords are not easily guessed and not made available to unauthorized persons.

So your job as a system administrator is to strike just the right balance between maximum utility and maximum safety, all the while bearing in mind that confidence in a secure machine.

There are many tools that Red Hat Linux provides to help you guard against intrusion, even to help you prevent intrusion into non-Linux machines that may reside on your network. Linux is designed from the beginning with security in mind, and in all of your tasks you should maintain that same security awareness

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Monitoring and Tuning Performance

2009-03-06T19:49:00.000-08:00

On a modern stand-alone system, Linux is pretty quick, and if it isn’t, there’s something wrong — something that is up to the system administrator to fix. You might have a number of people using the same fileserver,
mail server, or other shared machine, in which small improvements in system performance can mean a lot.

System tuning is an ongoing process carried by a variety of monitoringtools. Some performance decisions are made at installation time, while others are added or configured later.

Proper monitoring can detect a misbehaving application that might be consuming more system resources than it should or failing to exit completely on close. Through the use of system performance tools you can determine when hardware — such as memory, added storage, or even something as elaborate as a hardware RAID — should be upgraded for more cost-effective use of a machine in the enterprise. Possibly most important, careful system monitoring give you an early idea when a system component is showing early signs offailure, so that any potential downtime can be minimized.

Careful system monitoring and built-in configurability of Linux allows you to squeeze the best possible performance from your existing equipment, from customizing video drivers to applying special kernel patches to simply turning off unneeded services to free memory and processor cycles.

Backing Up and Restoring Files

2009-03-05T20:14:00.000-08:00

Until equipments becomes absolutely failure proof, and until people lose their desire to harm the property of others for personal benefits (and, truth be known, until system administrators become perfect), there is always a need to back up important files and data so that in the event of a failure of hardware, security, or administration, the system can be up and running again with minimal disruption. Only the system administrator may do this.

(Because of its built-in security features, Linux may not allow users to be able even to back up their own files to floppy disks.)

Again, knowing that file backup is your job is not enough. You need to formulate a proper strategy for making sure your system is not vulnerable to disruption. If you have a high-capacity tape drive and several restore diskettes, you might make a full system backup in every few days. If you are managing a system with scores of users, It is more sensible to back up user accounts and system configuration files, from the distribution CDs. (Don’t forget the applications you’ve installed separately from your Red Hat Linux distribution, especially including anything heavily customized!)

Once you’ve decided what to back up, you need to decide how frequently to perform backups and whether you wish to maintain a series of incremental backups — adding only the files that have changed since the last backup — or multiple full backups, and when these backups are to be performed — do you trust an automated, unattended process?

A strategy should be the maintenance of perfect backups without ever needing to resort to them. This means encouraging users to keep multiple copies of their own important files, all in their home directories, so that you are not being asked to mount a backup so as to restore a file that a user has corrupted.(And if the system is stand-alone, you as your own system administrator might want to make a practice of backing up configuration and other important files.)

The chances are that even if you’re working for a company, you’ll make these decisions — all your boss wants is a system that works perfectly, all the time. Backing up is only half the story, too. You need to formulate a plan for bringing the system back up in the event of a failure.

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Creating and Maintaining User Accounts

2009-03-05T19:44:00.000-08:00

Anyone cannot log on to a Linux machine. An account must be created for each user and — you guessed it — no one but the system administrator may do this. That’s simple enough.
But there are decisions that either you or your company must make. You might want users to select their own passwords, which would be easier for them to remember, but which probably would be easier for an external factor to crack. You might assign passwords, which is more secure in theory but which increases the chances that users will write them down on a conveniently located scrap of paper — a risk if many people have access to the area where the machine(s) is located. You might want that users must change their passwords periodically, and you can configure Red Hat Linux to prompt users to do so.

And what to do about old accounts? Perhaps someone has left the company. What happens to his or her account? You probably don’t want him or her to continue to have access to the company network. On the other hand, you don’t want to simply delete the account, because it might contain some essential data which is reside nowhere else.

There are aspects of your business that make World Wide Web access desirable, but you don’t want user"s spending their working hours surfing the Web.

The following issues and others are parts of the system administrator’s duties in managing user accounts. The administrator or his employer must establish the policies governing them— if in an enterprise, preferably in writing — for the protection of all concerned.

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Installing and Configuring Application Software

2009-03-04T05:10:00.000-08:00

It’s crucial and important for the new Linux system administrator to understand two characteristics that set Linux apart from other popular commercial operating systems: The first is the root or super user, and the second is that Linux is a multiuser operating system. Each user has (or shares) an account on the system, it may be on a separate machine or on a single machine with multiple accounts.Reason for there importance is found in the administration of application software — productivity programs.

Individual users can install some applications in their home directories — drive space set aside for their own files and customizations — these applications are not available to other users. Besides, if an application is to be used by more than one user, it needs to be installed higher up in the Linux file hierarchy, which is a job
of the system administrator only. (The administrator can even decide which users may use which applications by creating a “group” for that application and enrolling individual users into that group.)

Note:- The location of the installation of application usually matters only if you compile the application from source code; if you use a Red Hat Package Manager (RPM) application package, it automatically goes where it should.

Configuration and customization of applications is to some extent at the user’s
discretion, but not entirely. “Skeleton” configurations — administrator can determine default configurations . For example-
If there are particular forms, that are used throughout an enterprise, the system administrator would set them up or make them available by adding them to the skeleton configuration. The same applies, too, in configuring user desktops and determine what applications should appear on user desktop menus. Your company may not want the games that comes with modern Linux desktops to be available to users.

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Single Users vs. Multiusers vs. Network Users

Linux System Administrator

Installing and Configuring Servers

2009-03-02T06:41:00.000-08:00

In the world of Linux, the word “server” has a broader meaning than you might be used to. For instance, the standard Red Hat Linux graphical user interface (GUI) requires a graphical layer called XFree86. This is a server. It can run even on a standalone machine with one user account. It must be configured. (Fortunately, Red Hat Linux has made this a simple and painless part of installation on all).

Similarly, printing in Linux takes place after you have configured a print server. Again, this has become so easy. In certain areas the client-server nomenclature can be confusing, though. While you cannot have a graphical desktop without a server, you can have World Wide Web access without a Web server, File transfer protocol (FTP) access without running an FTP server, and Internet e-mail capabilities without ever starting a mail server. You may want to use these servers, all of which are included in Red Hat Linux, but then again you may not. And whenever a server is connected to other machines outside your physical control (remotely), there are security implications — you want users to have easy access to the things they need, but you don’t want to open up the system you’re administering to the whole wide world.

Linux distributions used to be shipped with all imaginable servers turned on by default. This was earlier thinking. But the realities of a modern, more dangerous world have dictated that essential servers are off unless they are manually enabled and configured. This duty falls to the system administrator. Administrator need to know what servers you need and how to employ them, and to be aware that it is a potential security nightmare to enable services that the system isn’t using and doesn’t need.

Linux System Administrator

2009-03-02T06:11:00.000-08:00

Every computer in the world has a system administrator. It may be that the majority of system administrators are probably those who decided as to what software and peripherals would be bundled with the machine when it was shipped. That status remains because the majority of users who acquire computers for use probably do little to change in the default values. But the minute the user makes some changes in applications and decides what softwares and applications to run he becomes a system administrator.

Such a high duty brings with it some responsibilities. No one whose computer is connected to the Internet, for instance, has been immune to the effects of poorly administered systems, as demonstrated by the Distributed Denial of Service (DDoS) and e-mail macro virus attacks that have shaken the online world in recent years. The scope of these acts of computer vandalism (and in some cases computer larceny) would have been greatly reduced if system administrators had a better understanding of their duties.

The Linux system administrator is more likely to understand the necessity of active system administration than are those who run whatever came on the computer, assuming that things came from the factory are properly configured. By its very nature as a modern, multiuser operating system, Linux requires a degree of administration greater than that of less robust home market systems. This means that even if you are using a single machine connected to the Internet by a dial-up modem — or not even connected at all — you have the benefits of the same system employed by some of the largest businesses in the world, and will do many of the things that the IT professionals employed by those companies are paid to do.

Administering your own system does involve a degree of learning, but it also means that in setting and configuring your own system you gain skills and understanding that raise you above mere “computer user” status.

By definition, the Linux system administrator is the person who has “root” access, which is to say the one who is the system’s “super user” (or root user). A standard Linux user has limitations. But the “root” user has unfettered access to everything — all user accounts, their home directories, and the files therein; all system configurations; and all files on the system. A certain body of thought says that no one should
ever log in as “root,” because system administration tasks can be performed more easily and safely through other, more specific means, which I will discuss in later posts.

Performing Preinstallation Evaluation

2009-03-02T03:16:00.000-08:00

Before getting into the actual installation phase, it is important that you take a moment and evaluate two things:

● The hardware the system is going to run on
● The server’s ideal configuration to provide the services you need

Let’s start by examining hardware issues.

Hardware
As with any operating system, before getting started with the installation process, you should determine what hardware configurations would work. Each commercial vendor publishes a hardware compatibility list (HCL) and makes it available on its web site. Red Hat’s hardware support site is at http://hardware.redhat.com, where you can search a compatibility database for systems or components. In general, most popular Intel-based configurations work without difficulty.

A general suggestion that applies to all operating systems is to avoid cutting-edge hardware and software configurations. While they appear to be really impressive, they haven’t had the maturing process some of the slightly older hardware has gone through. For servers, this usually isn’t an issue, since there is no need for a server to have the latest and greatest toys, such as 3-D video cards. After all, your main goal is to provide a highly available server for your users, not to play Doom. (Although it should be noted that I, myself, during my less responsible days as a junior-level administrator, found that Linux is wonderfully stable even while running Doom and being a file server.)

Installing Linux in a Server Configuration

2009-03-02T03:10:00.000-08:00

A key attribute in Linux’s recent success is the remarkable improvement in installation tools. What once was a mildly frightening process many years back has now become almost trivial. Even better, there are many ways to install the software; CD-ROMs are no longer the only choice (although they are still the most common). Network installations are part of the default list of options as well, and they can be a wonderful help when installing a large number of hosts.

In most cases, designating a system as a server will enable more services than you want. A single Linux system is capable of providing all sorts of services: disk, printers, mail, news, web, chat, and more. Many of these services are turned on automatically. But the reality is that most servers are dedicated to performing one or two tasks, and any other installed services simply take up memory and drag on performance, as well as provide hackers another avenue of attack.

This module discusses the installation process as it pertains to servers. This requires you to do two things: differentiate between a server and a client workstation and streamline a server’s operation in terms of its dedicated functions.

Interview Questions so far

2009-03-02T02:08:00.000-08:00

To review boot message which command can you use?
What command you execute to display the last five commands you have entered?
Which partitions might you create on mail server HDDs other than the root, swap and boot partitions?
Which partitioning tool is available in all distributions?
Which two commands can you use to delete directories?
Which file defines all users on your system?
What happens to a child process that dies and has no parent process to wait for it and what’s bad about this?
How do you fix a problem where a printer will cutoff anything over 1MB?
Which Linux distros do you have experience with?
Which tool would you use to update Debian / Slackware / RedHat / Mandrake / SuSE?
What is partitioning scheme for new web server and why?
What part of the operating system is Linux?
What distinguishes one distribution from another?
What are the performance implications of separating the GUI from the kernel?
Which of the following systems support mounting across networks:

A. Attached File System (AFS)B. Linux File System (Lfs)
C. Network File System (NFS)
D. Distributed File System (Dfs)

In which directory do Linux configuration files usually reside?
What does NIS stand for?
What function does a DC perform that NIS does not?

Active Directory

2009-02-28T19:14:00.000-08:00

So how does NIS stack up to Active Directory? Good question. The answer is “it doesn’t.” Active Directory was designed to be much more than what NIS was designed for. This really places the two into different classes of applications.

Active Directory (AD) is designed to be a generic solution to the problem of large sites that need to have their different departments share administrative control—something that the older Windows NT Domain model did very poorly. (Setting up interdomain trusts under NT often required a great deal of patience and a willingness to fix “broken” trusts on a regular basis.) AD is also an opportunity for Microsoft to fix many of its broken naming schemes and move toward an Internet-centric scheme based on DNS. The result is quite beastly and requires a lot of time to master. . However, in a smaller network, most folks will find that it looks and feels mostly like the old-style NT domains with some new whiz-bang features thrown in for good measure.

Don’t get me wrong, though—AD is a strong step in the right direction for Windows 2000 and presents solid competition for the Linux camp to think about how directory services can be better integrated into their designs. But despite what Microsoft tells you, AD will not solve all the world’s problems, let alone all of yours, in one easy step.

So does Linux have anything that compares to AD? Yes, actually, it does. Several implementations of LDAP (Lightweight Directory Access Protocol) now exist for Linux, and work is actively being done to allow NIS to tie into LDAP servers. (The RADIUS authentication protocol is also becoming more common.) LDAP is also interesting because it uses the same underlying technology that Active Directory uses in Windows 2000 and Windows .NET Server. This means that, in theory, it is possible to share LDAP databases between both your
UNIX and Windows systems and possibly unify authentication between them.

Domains

2009-02-28T19:10:00.000-08:00

For a group of Windows 2000 systems to work well together, they should exist in a domain. This requires a Windows 2000 Server system configured as a Domain Controller (DC). Domains are the basis of the Windows 2000 security model.

The basis of Linux’s network security model is NIS, Network Information Service. NIS is a simple text file–based database that is shared with client workstations. Each primary NIS server establishes a domain. Any client workstation wanting to join this domain is allowed to do so, as long as it can set its domain name. To set the domain name, you must use the root user—Linux’s equivalent to an Administrator user. Being part of the domain does not, however, immediately grant you rights that you would otherwise not have. The domain administrator must still add your login to the master NIS password list so that the rest of the systems in the network recognize your presence.

The key difference between NIS and Windows 2000 domains is that the NIS server by itself does not perform authentication the way a DC does. Instead, each host looks up the login and password information from the server and compares it to the user’s entered information. It’s up to the individual application to properly authenticate a user. Thankfully, the code necessary to authenticate a user is very trivial.

Another important difference is that NIS can be used as a general-purpose database and thus hold any kind of information that needs to be shared with the rest of the network. (This usually includes mount tables for NFS and e-mail aliases.) The only limitation is that each NIS map can have only one key, and the database mechanism doesn’t scale well beyond about 20,000 entries. Of course, a site with 20,000 users shouldn’t keep them all in a single NIS domain, anyway!

Neither Windows nor Linux requires use of domains for the base operating system to work. Nevertheless, they are key if you need to maintain a multiuser site with a reasonable level of security.

The Registry vs. Text Files

2009-02-27T18:45:00.000-08:00

I think of the Windows Registry as the ultimate configuration database—thousands upon thousands of entries, very few of which are completely documented, some located on servers and some located on clients. While it is possible to edit Registry entries manually, the fact that one does so using a graphical tool doesn’t make the process intuitive.

Consider this Windows .NET Server Registry setting: In HKEY_LOCAL_MACHINE\ SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters, set EnablePrefetcher to 0x00000003 to enable application and boot prefetching. Even assuming you know what prefetching is and want to enable it, that’s a daunting configuration change, and not one that I remember offhand.

If you’re not getting my message, I’m saying that the Windows Registry system is, at best very difficult to manage. Although it’s a good idea in theory, I’ve never emerged without injury from a battle with the Registry.

Linux does not have a registry. This is both a blessing and a curse. The blessing is that configuration files are most often kept as a series of text files (think of the Windows .INI files before the days of the Registry). This setup means you’re able to edit configuration files using the text editor of your choice rather than tools like regedit. In many cases, it also means you can liberally comment those configuration files so that six months from now you won’t forget why you set something up in a particular way. With most tools that come with Linux,configuration files exist in the /etc directory or one of its subdirectories.

The curse of a no-registry arrangement is that there is no standard way of writing configuration files. Each application or server can have its own format. Many applications are now coming bundled with GUI-based configuration tools, so you can do a basic setup easily and then manually edit the configuration file when you need to do more complex adjustments.

In reality, having text files to hold configuration information usually turns out to be an efficient method. Once set, they rarely need to be changed; even so, they are straight text files and thus easy to view when needed. Even more helpful is that it’s easy to write scripts to read the same configuration files and modify their behavior accordingly. This is especially true when automating server maintenance operations, an ability that is crucial in a large site with many servers.

Because Linux configuration files are text files, configuring systems automatically can be done quickly and easily without special tools. Simple scripts can be written to set the configuration values, making deployment of a new operating system, software package, or utility very easy. Windows requires third-party software (often licensed on a per-machine basis, which can become very expensive for large projects) to perform similar feats.

The Network Neighborhood

2009-02-27T01:23:00.000-08:00

The native mechanism for Windows folk to share disks on servers or with each other is through the Network Neighborhood. In a typical scenario, users attach to a share and have the system assign it a drive letter. As a result, the separation between client and server is clear. The only problem is that this method of sharing data is more people-oriented than technologyoriented: People have to know which servers contain which data.

Windows 2000 introduced a feature long available on UNIX systems: mounting. By mounting a share, Windows makes the share look as if it were just another directory located on the user’s local disk. This gives the illusion that a single unified directory structure exists, completely local to the machine. Microsoft’s Distributed File System (Dfs) allows a networkwide amalgamation of directories that can be configured and accessed as a directory tree. Windows .NET Server improves Dfs management features and allows a single server to host multiple Dfs trees.

Linux, using the Network File System (NFS), has supported the concept of mounting since its inception. This allows any directory to be “exported” for mounting on other systems. The mounted directory can be placed anywhere in the remote system’s directory tree. A common example of mounting partitions under Linux is with mounted home directories: The user’s home directories reside on a server, and the client mounts the directories at boot time (automatically). So /home exists on the client, but the contents of /home/username exist on the server.

Under Linux NFS, users never have to know server names or directory paths, and their ignorance is your bliss! As with Dfs, there are no more questions about which server to connect to. Users need not know when the need arises to change the server configuration.

Under Linux, you can change the names of servers and adjust this information on client-side systems without making any announcements or having to reeducate users. Anyone who has ever had to reorient users to new server arrangements is aware of the repercussions that may occur. Module 8 discusses the Linux Automounter, which dynamically mounts and unmounts partitions on an as-needed basis.

Printing works in much the same way. Under Linux, printers receive names that are independent of the printer’s actual host name. (This is especially important if the printer doesn’t speak TCP/IP.) Clients point to a print server whose name cannot be changed without administrative authorization. Settings don’t get changed without your knowing it. The print server can then redirect all print requests as needed. The Linux uniform interface will go a long way toward improving what may be a chaotic printer arrangement in your installation.
It also means you don’t have to install print drivers in several locations.

NOTE
If you intend to use Linux to serve Windows clients via the Samba package, you’ll still
have to deal with notifying users about server shares and printer assignments. You can
read more about Samba in Module 18.

Separation of the GUI and the Kernel

2009-02-26T07:49:00.000-08:00

Taking a cue from the Macintosh design concept, Windows developers integrated the graphical user interface (GUI) with the core operating system. One simply doesn"t exist without the other. The benefit to this coupling of the operating system and the user interface is consistency in the appearance of the system. Although Microsoft does not impose rules as strict as Apple’s with respect to the appearance of applications, most developers tend to stick with a basic look and feel among applications.

On the other hand, Linux has kept the two elements—user interface and operating system—separate. The X Window System interface(GUI) is run as a user-level application, which makes it more stable. If the GUI (which is very complex for both Windows and Linux) fails, Linux’s core does not go down with it unlike that of the windows. The X Window System also differs from the windows 2000 GUI in that it isn’t a complete user interface in itself but rather It only defines how basic objects should be drawn and manipulated on the screen.

NOTE:-
Unfortunately, Due to the lack of tight integration of the X Window System into Linux has a downside. While the operating system is very robust, X Windows is somewhat more sensitive to problems with certain hardware or graphics settings. The Linux version of the “three-finger salute” is CTRL-ALT-BACKSPACE, which kills X.

The most significant feature of the X Window System lies in its ability to transmit windows across a network and display them on another workstation’s screen. This allows a user sitting on Host A to log in to Host B (remote connection), run an application on Host B, and have all of the output routed back to Host A. It is possible for two people to be logged in to the same machine, running a Linux equivalent of Microsoft Word (such as OpenOffice, WordPerfect, or StarOffice) at the same time. Even when using Terminal Services, Windows 2000 and Windows XP users are limited to a single user at a time running a given application and using the display.

In addition to the X Windows core, a window manager is needed to create a useful environment. Most Linux distributions (including Red Hat) come with several window managers and include support for GNOME and KDE, both of which are available on other variants of UNIX as well. When set as default, either GNOME or KDE offers an environment that is friendly even to the casual Windows user.

So which is better—Windows 2000 or Linux—and why? That depends on what you are trying to do. The integrated environment provided by Windows 2000 is convenient, and because it is more standardized, it is less complex than Linux, but it lacks the X Windows feature that allows applications to display their windows across the network on other workstations. Windows 2000’s GUI is consistent but cannot be turned off, whereas X Windows doesn’t have to be running (and consuming valuable memory) on a server.

Determining Technical Differences Between Windows and Linux

2009-02-26T07:38:00.000-08:00

As you might imagine, the differences between Microsoft Windows 2000 or Windows .NET Server and the Linux operating systems cannot be completely discussed in the confines of this section. Throughout these modules, topic by topic, you’ll examine the specific contrasts between the two systems. In some modules, you’ll find that the text doesn’t derive any comparisons, because a major difference doesn’t really exist.

Before attacking the details, take a moment to discuss the primary architectural differences between the two operating systems. Historical differences between Linux and Windows are steadily disappearing, but some still persist.

Single Users vs. Multiusers vs. Network Users
Windows was designed according to the “one computer, one desk, one user” vision of Microsoft’s cofounder Bill Gates. For the sake of discussion, I’ll call this philosophy single-user. In this arrangement, two people cannot work in parallel running (for example) Microsoft Word on the same machine at the same time. Using Terminal Services in Windows 2000 or Windows XP allows remote use of one computer from another but is still bound by the single-user paradigm.

The Windows .NET Server products, which are unfinished as of this writing, continue to add terminal features to enable more than one user to access the server simultaneously. Linux borrows its philosophy from UNIX. When UNIX was originally developed at Bell Labs in the early 1970s, it ran on a PDP-7 computer that needed to be shared by an entire department. It required a design that allowed multiple users to log in to the central machine at the same time. Various people could edit documents, compile programs, and do other workat the exact same time. The operating system on the central machine took care of the “sharing” details, so that each user seemed to have an individual system. This multiuser tradition continues through today, on other UNIXs as well. And since Linux’s birth in the early 1990s, it has supported the multiuser arrangement.

Today, the most common implementation of a multiuser setup is to support servers— systems dedicated to running large programs for use by many clients. Each member of a department can have a smaller workstation on the desktop, with enough power for day-to-day work. When they need to do something requiring significantly more CPU power or memory, they can run the operation on the server.

Linux, Windows 2000, and Windows .NET Server are all capable of providing services such as databases over the network. Users of this arrangement can be called network users, since they are never actually logged in to the server but rather send requests to the server. The server does the work and then sends the results back to the user via the network. The catch in this case is that an application must be specifically written to perform such server/client duties. Under Linux, a user can run any program allowed by the system administrator on the server without having to redesign that program. Most users find the ability to run arbitrary programs on other machines to be of significant benefit.

What do I have to pay for “free” software?

2009-02-25T09:21:00.001-08:00

The short answer is you probably don’t. Red Hat is one of many Linux distributions that allow free download, so if you have a high-bandwidth Internet connection, you can slurp down the files, burn some installation CDs, and install the software without paying one red cent. Many distributions are available on CDs from third parties who
charge less than $5 each. Some people prefer to pay for support or to buy boxed versions of the software, either to support the company whose product they use, or to ensure that they get timely answers to their questions. Free Software does not mean you’re entitled to have it without paying for it, but it does mean that if someone is entitled to have it, they can give it to you if they wish.

Red Hat Linux Distribution

2009-02-25T09:20:00.000-08:00

Red Hat’s Linux distribution is very popular, especially in the United States. However, many other excellent distributions exist, and none has the exclusive rights to Linux. I use Red Hat Linux, and presumably the reason you’re reading this guide is so that you can use it, too. But once you become more comfortable with Linux, you can create your own distribution if you desire. The freedoms provided by the GPL allow you to customize and even sell Linux if you wish.

Is it true that the operating system’s correct name is GNU/Linux?

2009-02-25T09:18:00.000-08:00

That depends upon whom you ask. Those with the GNU Project, having worked long and hard to create the tools that make an operating system useful (utilities, compilers, and applications), want their diligence recognized. Because nearly all “Linux” systems consistlargely of GNU tools and the Linux kernel, this isn’t unreasonable. On the other hand, many people feel that GNU/Linux is too awkward to use as the primary name for an operating
system. In any event, the choice is up to you: Linux or GNU/Linux, it’s all good.

Defining Free Software and the GNU License

2009-02-25T08:52:00.001-08:00

In the early 1980s, Richard Stallman began a movement within the software industry. He preached (and still does) that software should be free. Note that by free, he doesn’t mean in terms of price, but rather free in the same sense as freedom. This meant shipping not just a product, but the entire source code as well.

Stallman’s policy was obviously a wild departure from the early eighties mentality of selling prepackaged software, but his concept of free software was in line with the initial distributions of UNIX from Bell Labs. Early UNIX systems did contain full source code. Yet by the late 1970s, source code was typically removed from UNIX distributions and could be acquired only by paying large sums of money to AT&T. The Berkeley Software Distribution (BSD) maintained a free version but had to deal with many lawsuits from AT&T until it could be proved that nothing in the BSD was from AT&T.

The idea of giving away source code is a simple one: A user of the software should never be forced to deal with a developer who might or might not support that user’s intentions for the software. The user should never have to wait for bug fixes to be published. More important, code developed under the scrutiny of other programmers is typically of higher quality than code written behind locked doors. The greatest benefit of free software, however, comes from the users themselves: Should they need a new feature, they can add it to the program and then contribute it back to the source, so that everyone else can benefit from it.

From this line of thinking has sprung a desire to release a complete UNIX-like system to the public, free of license restrictions. Of course, before you can build any operating system, you need to build tools. And this is how the GNU project was born.

NOTE
GNU stands for GNU’s Not UNIX—recursive acronyms are part of hacker humor. If you don’t think it’s funny, don’t worry. You’re still in the majority.

What Is the GNU Public License?
The most important thing to emerge from the GNU project has been the GNU General Public License (GPL). This license explicitly states that the software being released is free, and that no one can ever take away these freedoms. It is acceptable to take the software and resell it, even for a profit; however, in this resale, the seller must release the full source code, including any changes. Because the resold package remains under the GPL, the package can be distributed free and resold yet again by anyone else for a profit. Of primary importance is the liability clause: The programmers are not liable for any damages caused by their software. More about GNU and the GPL can be found at http://www.gnu.org.

It should be noted that the GPL is not the only license used by free software developers (although it is arguably the most popular). Other licenses, such as BSD and Apache, have similar liability clauses but differ in terms of their redistribution. For instance, the BSD license allows people to make changes to the code and ship those changes without having to disclose the added code. (The GPL would require that the added code be shipped.) For more information about other open-source licenses, check out http://www.opensource.org.

LINUX ADMINISTRATION GUIDE

Shadow Password Suite

Installing Thunderbird E-mail client on Red-hat/CentOS Linux

Bash(bourne again shell)

umask

About LDAP

Linux ARP And Commands

Understanding ext3 file system and its advantages

Concept of the i-Nodes and Superblocks in Linux/Unix System

Remote Shell: rsh

Languages Internal/external to Oracle database and developers suite

Linux text to speech festival

Installing vlc player in Fedora/Red Hat/ CentOS

Virtualization Grid Computing

The Oracle"s Application Server

Opening And Extracting .rar Files in Linux/Unix system

List file inside rar archive

Open (x) files

Install WEBMIN to Graphically Administer Your Linux Server

Tracking Processes In UNIX/LINUX System

Brief Introduction To Oracle And Database Management System

Install Skype(pc2pc calling software) On Linux 64 bits

Basics of User and Group Management

Install Vuze(Azureus) Bittorent client on Linux 64 bit

NFS Overview

Initialization Scripts

File Permissions 2

File Permissions 1

Printer Configuration

Starting and Stopping the Network

Post-Installation Configuration

Network Configuration

Navigating the Filesystem

About Shell Prompt

Exploring Logical Volume Management

Troubleshooting With FSCK

Mounting Directories

Tuning

Formatting a partition

Basic Linux Formats

Installing and configuring Vmware2 to Run Linux (RHEL-5)

Adding A New Hard Drive

Managing partitions with fdisk

Managing Partitions

Partition Schemes

Basic Linux Directory Structure

Ownership

Understanding Filesystem Hierarchy Standard

Other Text editor

Basic VI commands

Using the vi Editor On Linux

Command Combinations

Manipulating Files

Managing Files

Setting up Files And Directories

Starting at the command line

Using the Red Hat Package Manager

Determining a Server’s Functions

Methods of Installation

Dual-Booting Issues

Uptime

Server Design

Using Tools to Monitor Security

Configuring a Secure System

Monitoring and Tuning Performance

Backing Up and Restoring Files

Creating and Maintaining User Accounts

Installing and Configuring Application Software

Installing and Configuring Servers

Linux System Administrator

Performing Preinstallation Evaluation

Installing Linux in a Server Configuration

Interview Questions so far

Active Directory

Domains

The Registry vs. Text Files

The Network Neighborhood

Separation of the GUI and the Kernel

Determining Technical Differences Between Windows and Linux

What do I have to pay for “free” software?