To enter Maintenance Mode, at the ESX console type:
vimsh -n -e /hostsvc/maintenance_mode_enter
To exit Maintenance Mode type:
vimsh -n -e /hostsvc/maintenance_mode_exit
To display whether the ESX Server is currently in maintenance mode or not type:
vimsh -n -e"hostsvc/hostsummary" | grep inMaintenanceMode
Falling down is not defeat. Defeat is when you refuse to get up.
All the best for your all future assignments in your life and happy LINUX.
Any queries related to Linux can send to mailto:shankermcsa@yahoo.com
Trademarks: Red Hat is a registered trademark of Red Hat, Inc. Linux is a registered trademark of Linus Torvalds. All other trademarks are the property of their respective owners.
UNIX History
First version created in Bell Labs - 1969
AT&T licenses source code for low cost
GNU Project / FSF
GNU Project started in 1984
r Goal: Create a "free" UNIX clone
r By 1990, nearly all required userspace applications created
r gcc, emacs, etc
l Free Software Foundation
r Non-profit organization that manages the GNU project
Linux Origins
l Linus Torvalds
m Finnish college student in 1991
m Created Linux kernel
l Linux kernel + GNU applications = complete, free, UNIX-like OS
Recommended Hardware Specifications
l Pentium Pro or better with 256 MB RAM or
l 64-bit Intel/AMD with 512 MB RAM
l 2-6 GB disk space
l Bootable CD
l Other processor architectures supported
l Itanium 2, IBM Power, IBM Mainframe
Virtual Consoles
l Multiple non-GUI logins are possible through the use of virtual consoles
l There are by default 6 available virtual consoles
l Available through Ctrl-Alt-F[1-6]
l If X is running, it is available as Ctrl-Alt-F7
The Xorg GUI Framework
l Modern, free implementation of X11
l Highly flexible framework for displaying graphical applications and environments
l Completely network-transparent client/server architecture
l System can be configured to present a graphical login screen on Ctrl-Alt-F7
The Xorg Graphical Environments
l Collections of applications that provide a graphical working environment with a consistent look-and-feel
m GNOME - The default desktop environment
m KDE - Environment based on the Qt toolkit
Starting Xorg
l Nothing needed if system boots to a graphical login. Just authenticate.
l If system boots to a virtual console login, Xorg must be started manually
m Run startx to manually start Xorg
Getting Help
Don't try to memorize everything!
Many levels of help
m whatis
m command --help
m man and info
m /usr/share/doc/
m Red Hat documentation
Extended Documentation
l The /usr/share/doc directory
m Subdirectories for most installed packages
m Location of docs that don't fit elsewhere
r Example configuration files
r Html/pdf/ps documentation
r License details
Some Important Directories
The home directories
m /root, /home/username
l The bin directories
m /bin, /usr/bin, /usr/local/bin
m /sbin, /usr/sbin, /usr/local/sbin
l Foreign filesystem mountpoints
m /media and /mnt
l /etc holds system config files
l /tmp holds temporary files
l /boot holds the kernel and bootloader
l /var and /srv hold server data
l /proc and /sys hold system information
l The lib directories hold shared libraries
m /lib, /usr/lib, /usr/local/lib
Absolute and Relative Pathnames
Absolute pathnames begin with a forward slash
l Complete "road map" to file location
l Can be used anytime you wish to specify a file name
Relative pathnames do not begin with a slash
l Specifies location relative to your current working directory
l Can be used as a shorter way to specify a file name
COMMANDS
If OS is not recognizing the SATA HDD
boot: linux all-generic-ide noapic noiapic
After installing the OS go to rescue mode and edit the grub.conf
#vi /etc/grub.conf
Root (hd0,0)
Kernel (vmlinuz-2.6.9-22.EL ro root=LABEL=/ linux all-generic-ide noapic noiapic rhgb quiet
Initrd /initrd-2.6.9.22.EL.img
Basic commands:
#echo $SHELL shows the default SHELL
#cat /etc/shells shows other existing Shells
#vi /etc/login.defs login information file
#chvt to switch to other terminal
#chage -l <username> to see the A/c policies.
#chage <username> to modify A/c policies
#chage -E -1 <username> to make account never expires.
#date --set "-----------"
Present Working Directory
#pwd
Listing Commands:
#ls
#ls -a
#ll
#ls -ld <filename>
#ll <filename>
#ls -al
Creating the Directory and Files
#mkdir <dir>
#mkdir <dir1> <dir1> <dir1>
#mkdir -p d1/d2/d3
Changing Directory
#cd <dir>
Creating a File
#cat > <filename>
Ctrl+d
#touch <filename>
Copy file
#cp <source path> <destination path>
Move and Renaming file
#mv <source path> <destination path>
Deleting file
#rm -rf <filename>
Append an existing file
#cat >> <filename>
Determining File Content
Files can contain many types of data
l Check file type with file before opening to determine appropriate command or application to use
l file [options] <filename>...
User & Group Admin
Authentication information is stored in plain text files:
o /etc/passwd
o /etc/shadow
o /etc/group
o /etc/gshadow
Changing Your Identity
To change your password, run passwd
m Insecure passwords are rejected
To start a new shell as a different user:
o su
o su -
o su username
o su - username
User Information Commands
Find out who you are
m whoami
Find out what groups you belong to
m groups, id
Find out who is logged in
m users, who, w
Login/reboot history
m last
Syntax:
#useradd <username> to create user
#groupadd <groupname> to create group
#useradd -u <uid> <username>
#groupadd -g <gid> <groupname>
#userdel <username> to delete user
#userdel -r <username> to delete user including home dir.
#passwd <username> to assign passwd
#passwd -S <username> shows passwd set to user or not
#passwd -d <username> to remove passwd
#id <username>
#finger <username>
Syntax: useradd <option> <username>
#usermod -G <groupname> <username>
#usermod -u <uid> <username>
#usermod -d <dir> <username> to change home directory
#usermod -s /bin/ksh <username> to change default Shell
#usermod -c "admin" <username> to put comments
#usermod -u <uid> -o <username> to change UID
#usermod -g <gid> <groupname> to change GID
#usermod -l <newusername> <oldusername> to rename user
#groupmod -n <newgroup name> <oldgroup name> to rename group
#gpasswd -a <username> <groupname> to add members of group
#gpasswd -M <username>,<username> <groupname>
#chown <new owner>.<new group> <file/dir name>
#chgrp <new group name> <file name>
#vi /etc/passwd (backup file: /etc/passwd-)
#vi /etc/group (backup file: /etc/group-)
#vi /etc/shadow (backup file: /etc/shadow-)
#tail <filename>
#head <filename>
Links
#ln <source file path> <destination file path> Hard Link
#ln -s <source file path> <destination file path> Soft Link
Permission of a File
Symbolic Notation: Read=r, Write=w and execute=x
Numeric Notation: Read =4, Write=2 and Execute=1
r w x (Where 1 = on and 0 = off)
1 0 0 =4
0 1 0 =2
0 0 1 =1
UMASK: Universal Mask is a value which is subtracted from the full permissions to generate the default permissions.
Root User Normal User
The full permission of a File is 666 The full permission of a File is 666
-rw- rw- rw- 666 -rw- rw- rw- 666
-rw- r- - r- - 644 -rw- r- - r- - 664
-------------------------------- -------------------------------
-w- -w- 022 (umask) -w- -w- 002 (umask)
The full permission of a Directory is 777 The full permission of a Directory is 777
-rwx rwx rwx 777 -rwx rwx rwx 777
-rwx r- x r- x 755 -rwx r- x r- x 775
-------------------------------- --------------------------------
-w- -w- 022 (umask) -w- -w- 002 (umask)
Syntax:
#umask to see the umask value
#vi /etc/bashrc to change umask value permanently
#chmod <numeric permission> <file/dir>
e.g. #chmod 777 <file/dir>
Special Permissions
SUID Value is 4
SGID Value is 2
Sticky Bit Value is 1
Normally, users with write permissions to a directory can delete any file in that
directory regardless of that file's permissions or ownership
With the sticky bit set on a directory, only the owner of a file can delete the file
Example: /tmp
drwxrwxrwt 12 root root 4096 Nov 2 15:44 tmp
ACL
#mount -o remount,acl <mount point> enable the partition with ACL properties
#setfacl -m u:<uname>:<permission> <filename> applying acl to the user level
#setfacl -x u:<uname>:<permission> <filename> to remove the acl
#setfacl -m g:<gname>:<permission> <filename> applying acl to the group level
#getfacl <filename> to check the acl permission
Note: when applying ACL present working directorie must be acl directorie and to make it permanent write inside /etc/fstab
Attribute
#chattr +i <filename>
#chattr -i <filename>
#chattr +a <filename>
#chattr -a <filename>
#lsattr <filename>
Special Users
SUDO
#useradd admin
#passwd admin
#vi /etc/sudoers or #visudo put the admin user in sudo file.
#sudo su - to get the root privileges as a sudo user.
#grep sudo /var/log/secure
Network User
Usr Profiles
#vi /etc/default/useradd
# useradd defaults file
GROUP=100
HOME=/home
INACTIVE=-1
EXPIRE=2008-01-01
SHELL=/bin/bash
SKEL=/etc/skel (user profiles)
System Initialization
Boot Sequence Overview
BIOS Initialization
§ Peripherals detected
§ Boot device selected
§ First sector of boot device read and executed
Boot Loader Components
GRUB and grub.conf
Starting the Boot Process: GRUB
The Chicken/Egg Module Problem and the Initial RAM Disk
To mount the root filesystem, the kernel typically needs to load modules
o Examples: ext3, jbd, raid1, scsi_mod
An initial RAM disk provides modules
o Compressed cpio archive containing modules, other material
o Created at install time
o Specific to a particular hardware and software platform
Made available to the kernel by GRUB
Use mkinitrd to rebuild
o Example:
o mkinitrd /boot/initrd-$(uname -r).img $(uname -r)
Kernel Initialization
init Initialization
Run Levels
§ init defines run levels 0-6, S, emergency
§ The run level is selected by either
· the default in /etc/inittab at boot
· passing an argument from the boot loader
· using the command init new_runlevel
§ Show current and previous run levels
/etc/rc.d/rc.sysinit
§ Important tasks include:
§ Activate udev and selinux
§ Sets kernel parameters in /etc/sysctl.conf
§ Sets the system clock
§ Loads keymaps
§ Enables swap partitions
§ Sets hostname
§ Root filesystem check and remount
§ Activate RAID and LVM devices
§ Enable disk quotas
§ Check and mount other filesystems
§ Cleans up stale locks and PID files
/etc/rc.d/rc
Daemon Processes
·A daemon process is a program that is run in the background, providing some system service
·Two types of daemons:
o standalone
o Transient - controlled by the "super-daemon" xinetd
System V run levels
· Run level defines which services to start
o Each run level has a corresponding directory:
I tend to install and reinstall operating systems quite frequently on my home system. With my hectic schedule, I don’t have time to sit down to reinstall and configure every last program. Although it is arguably easier to use a backup of my system for day-to-day mishaps, I tend to change out peripherals a lot and restoring a system that does not have certain drivers “cleaned out” tends to wreak havoc on a new configuration. To make this process go a bit faster, two years ago I created a “Ghost Image” of my hard drive after doing a basic install. Now, instead of it taking a few hours of toiling away to reinstall a system, I can do this all in about 15 minutes with only half a dozen quick mouse clicks. The trick is to use Norton Ghost or any other imaging software and Microsoft Sysprep.
Part 1: Install XP and Sysprep
[SysprepMassStorage] section in the form PCI\VEN_###&DEV_#### = PATH_TO_DRIVER_ON_IMAGED_DRIVE where VEN_#### should be replaced by the Vendor ID number (i.e. VEN_1234) and the DEV_#### should be replaced by the Device ID number (DEV_1234). This information can usually be found in the specifc driver INF files. Here is an example for adding the VMWare SCSI controller driver to sysprep.inf[SysprepMassStorage]
….snipped out windows mass storage driver list….
PCI\VEN_104B&DEV_1040=C:\Drivers\Mass\VMWare\vmscsi.inf
testuser account with administrative privileges. Use this account to install and configure all the software and policies on the system.testuser account to the Administrator start menu. (Note: This is necessary as some installers do not create start menu items in All Users but within the testuser profile only. This leaves some items missing on the Administrator start menu.)c:\Documents and Settings\Default User. If you don’t understand then refer to Microsoft KB291586.testuser account. Make sure that c:\Documents and Settings\testuser has been deleted too.c:\sysprep.sysprep.inf file by running setupmgr.exe. This a tool Microsoft provides for creating an answer file so the restore doesn’t involving asking the normal setup questions. The basic steps are below: setupmgr.exe.The process of creating a basic sysprep.inf file is now completed.
c:\drivers.c:\sysprep\sysprep.inf in Notepad and add the following lines to the relavent sections (if the heading doesn’t exist, create it):[Unattended]
DriverSigningPolicy=Ignore
UpdateInstalledDrivers=Yes
OemPNPDriversPath=drivers\hardware_cat\driver_dir\driver_inf;(repeat);
[SysPrep]
BuildMassStorageSection=Yes
[SysprepMassStorage]
sysprep.inf yet! OemPNPDriversPath points to the c:\drivers directory created earlier. For organizational purposes, I split up my custom driver files based on category (i.e. hardware_cat in the example above). For example, all video drivers go under c:\drivers\video and network drivers under c:\drivers\network. In each of those directories, the specific driver bundles are placed with their driver inf files (i.e. driver_dir). For example, the latest nVidia drivers would go into c:\drivers\video\nVidia\. The last part is refering to driver_inf is just that, the name of the inf file. For example, for the latest nVidia driver, the path would be c:\drivers\video\nVidia\nv4_disp.inf. In sysprep.inf, the path would be written as OemPNPDriversPath=drivers\video\nVidia\nv4_disp.inf;. Do not forget the semi-colon as a separator. For the next driver, repeat the procedure by placing the path after the semi-colon without leaving a space. Once all the drivers are added, save the file.c:\sysprep\sysprep -bmsd. This will build the Windows XP standard mass storage drivers section.InstallFilesPath which usually points to c:\sysprep\i386. I usually copy the contents of my XP CD’s i386 directory into c:\sysprep\i386. This isn’t necessary.[SysprepMassStorage] section as detailed above.C:\sysprep\sysprep.exe.Sysprep is now complete. Part 2 contains instructions on imaging the partition.
Part 2: Norton Ghost Instructions
I’m using an older version of Ghost because the newer versions are trumped by Acronis True Image in terms of having less bugs and more features. However, DOS based Ghost has worked fine for me for most systems. If Ghost fails on your system for some reason, try imaging with Acronis True Image trial version. The basic idea is boot off a floopy or CD on the source system, start the backup program, backup the entire drive as an image file onto some other device (portable hard drive or another drive in the system) and then restoring (as necessary) from that image file onto a target system.
The basic Ghost process is as follows:
Note: You must do this on another machine that has Ghost installed. If you boot the Sysprep machine accidentally then you must go through the entire Sysprep checklist again. Trust me, I learned the hard way more than once.
ghost.exe. The default path is usually fine.The steps above are a very quick summary so I recommend that anyone truly interested in doing this to head over to Vernalex’s site for an in-depth Sysprep Guide. Along with a lot more detail of the entire process, he has various tools to make everything a little easier. The best utility on his site has to be the Sysprep Driver Sanner tool. It makes the process of adding hardware drivers much easier than the manual process above. Instructions on using it are on his site.
This completes the imaging process. Part 3 includes miscellaneous notes.
Update (2.24.2006): I’ve gotten some great tips from both the comments at Digg and below. Let me address a few of those.
pagefile.sys and hibernat.sys to save a few hundred megs of space in the final image. Thanks master_of_fm.In my opinion, the best solution is to have one basic machine for each HAL to make all of your images from. Follow all the steps above but do not reseal the system. Drop down to Ghost (or whatever backup utility you are using) and create an image of the system. In the future, creating compatible images for newer machines would be as simple is restoring the almost-complete Sysprep image and adding in new drivers for the chipset, mass storage controller and anything else you need. Then resealing the system and imaging it for a viable deployment image. Again, I am not an expert so hopefully the Sysprep gurus can step in to address this one if I went wrong somewhere.
Update (3.8.2006): If after rebooting, the install hangs at mup.sys or agp440.sys then it’s more than likely a HAL problem. Refer to the previous update to change your HAL. For most modern day single-processor machines make sure your HAL is changed from Uniprocessor ACPI to Advanced Configuration and Power Interface (ACPI) PC. You can find this setting in Control Panel -> System -> Hardware tab -> Device Manager -> click (+) next Computer -> right click the HAL shown and pick Update Driver -> Install from a list or specific location (Advanced) -> Don’t search. I will choose the driver to install. -> then pick the proper HAL -> hit next/okay until you finish. Now reboot and run through the Sysprep instructions again.
It took me a few tries to finally make an image that restored properly when I first started but, like riding a bike, it’s second nature now. Be ready to experience frustration but in the end it is worth having this knowledge. Again, read the comments below and at Digg to see how others have achieved this process. I don’t claim to be an expert (I’m just a med student by day) but I certainly hope this helps someone.
Introduction
Apache Tomcat is the servlet container that is used in the official Reference Implementation for the Java Servlet and JavaServer Pages technologies. The Java Servlet and JavaServer Pages specifications are developed by Sun under the Java Community Process.
Packages required
Java 2 SDK, Standard Edition v1.4.1-01 http://www.blackdown.org/java-linux/java-linux-d2.html
Ant 1.6.5 http://ant.apache.org/
JavaBeans Activation Framework http://java.sun.com/products/javabeans/glasgow/jaf.html
Javamail http://java.sun.com/products/javamail/
jakarta-tomcat-5.X http://jakarta.apache.org/site/downloads/downloads_tomcat-5.cgi
Installing Java 2 SDK
Untar/unzip j2sdk package
$cp j2sdk1.4.1 /usr/local/
$ln –s j2sdk1.4.1 j2sdk
set JAVA_HOME
$export JAVA_HOME=/usr/local/j2sdk
add PATH for java binary
$export PATH=$PATH:$JAVA_HOME/bin
verify javac command gives some output
root@tux:~# javac
Usage: javac
where possible options include:
-g Generate all debugging info
-g:none Generate no debugging info
-g:{lines,vars,source} Generate only some debugging info
Installing ANT
Untar ant-
$tar xvzf ant-
move untared directory this to /usr/local/ant
$mv ant-
set ANT_HOME
export ANT_HOME=/usr/local/ant
add PATH for ant binary
export PATH=$PATH:$ANT_HOME/bin
verify ant binary is on PATH
root@tux:~# ant
Buildfile: build.xml does not exist! (don’t worry about this message, this was just to check ant in on path or not)
Installing JavaBeans Activation Framework
$unzip jaf-
$cd jaf-
copy activation.jar to /usr/local/j2sdk/lib
$cp activation.jar /usr/local/j2sdk/lib
set CLASSPATH for this jar
$export $CLASSPATH=/usr/local/j2sdk/lib/activation.jar
Installing Javamail
$unzip javamail-
$cd javamail-
copy mail.jar to /usr/local/j2sdk/lib
$cp mail.jar /usr/local/j2sdk/lib
set CLASSPATH for this jar
export $CLASSPATH=$CLASSPATH:/usr/local/j2sdk/lib/mail.jar
All set for tomcat
Just again verify all environment variables
$echo $JAVA_HOME
$echo $ANT_HOME
$echo $PATH
$echo $CLASSPATH
now we have two options to install tomcat
1. using source
2. using binary
Tomcat Installation from source
Untar source
$tar xvzf jakarta-tomcat-5.x.x-src.tar.gz
$cd jakarta-tomcat-5.x.x
start building source
this build process is controlled by build.properties
add this content to it: # ----- Proxy setup -----# Uncomment if using a proxy server.#proxy.host=proxy.domain#proxy.port=8080#proxy.use=on# ----- Default Base Path for Dependent Packages -----# Replace this path with the directory path where# dependencies binaries should be downloaded.base.path=/usr/share/java
$ant build
Buildfile: build.xml
check.source:
check.source.depends:
once this is done without any errors, copy build to appropriate location
$cp jakarta-tomcat-5.x.x/jakarta-tomcat-5/build /usr/local/tomcat
Installation done from source
Tomcat Installation from binary
Download and untar jakarta-tomcat-5.x.x.tar.gz
$tar xvzf jakarta-tomcat-5.x.x.tar.gz
move untared directory to /usr/local/tomcat
$mv jakarta-tomcat-5.x.x /usr/local/tomcat/
Installation done using binary.
Configuring Tomcat
Optionally set CATALINA_HOME to /usr/local/tomcat/
$export $CATALINA_HOME=/usr/local/tomcat/
make changes in configuration, go to conf dir
$cd /usr/local/tomcat/conf
to change port of tomcat edit server.xml Connector port="8080" tag
you can add various roles and assign these roles to different users by making changes in tomcat-users.xml
you can write a init script for tomcat startup/shutdown
#!/bin/sh
export JAVA_HOME=/usr/local/j2sdk
export PATH=$PATH:/usr/local/j2sdk/bin/
case "$1" in
start)
echo -n "Starting tomcat: "
/usr/local/tomcat/bin/startup.sh
;;
stop)
echo -n "Shutting down tomcat: "
/usr/local/tomcat/bin/shutdown.sh
;;
*)
echo "Usage: $0 {start|stop}"
exit 1
esac
exit 0
copy this content to /etc/init.d/tomcat.server
give execute permission
chmod +x /etc/init.d/tomcat.server
on debian do
$update-rc.d tomcat.server defaults
Testing setup
Start tomcat
root@tux:~# /etc/init.d/tomcat.server start
Starting tomcat: Using CATALINA_BASE: /usr/local/tomcat
Using CATALINA_HOME: /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JAVA_HOME: /usr/local/jdk
Check in process list for successful startup
1834 pts/6 S 0:15 /usr/local/jdk/bin/java -Djava.endorsed.dirs=/usr/local/tomcat/common/endorsed -classpath /usr/loc
1835 pts/6 S 0:00 /usr/local/jdk/bin/java -Djava.endorsed.dirs=/usr/local/tomcat/common/endorsed -classpath /usr/loc
1836 pts/6 S 0:01 /usr/local/jdk/bin/java -Djava.endorsed.dirs=/usr/local/tomcat/common/endorsed -classpath /usr/loc
also verify it its listening on port specified in server.xml
root@tux:~# netstat -nap | grep java
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN 11507/java
Shutdown tomcat
root@tux:~# /etc/init.d/tomcat.server stop
Shutting down tomcat: Using CATALINA_BASE: /usr/local/tomcat
Using CATALINA_HOME: /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JAVA_HOME: /usr/local/jdk
Next open a browser and type http://
For eg http://machine:8080
You will see tomcat page
You can admin tomcat from http://
eg
http://machine:8080/admin
manager url http://
give username/password specified in tomcat-users.xml with admin/manager role
like
