OpenGurukul : Operating System : Linux

LINUX

By
OpenGurukul.com
Free/Open Source Software Laboratory

LINUX

Module : History

www.opengurukul.com 2

Unix : History
UNIX Variants
IBM AIX
Oracle/Sun Solaris
HP HP-UX


Unix : History
LINUX (Unix like operating system) Distributions
Redhat Fedora (Free Edition), RHEL (Redhat
Enterprise Linux)
Novell SLED(Suse Linux Enterprise Desktop),
SLES (Suse Linux Enterprise Server)
Canonical Ubuntu (derived from Debian)
Oracle Enterprise Linux (derived from RHEL)
CentOS (derived from RHEL)


LINUX

Module : File Systems


Linux : File Systems
Computers store information in things called files.
A file is like a sheet of paper with something writ-
ten on it.
Files are stored in things called directories (popu-
larly known as folders on windows).


Linux : File Systems : pwd
pwd : print name of current/working directory

Usage:
$ pwd

Example:
$ pwd
/home/sachin
$ echo $HOME
/home/sachin
$

Linux : File Systems : cd
cd : change directory
Used to change current working directory
Usage:
$ cd <dirname>

Example:
$ cd /tmp
$ pwd
/tmp
$

Linux : File Systems : cd to home
directory
cd ~ : cd to home directory cd : cd without arguments to go
to home directory

Example :
Example :
$ cd ~ ; pwd
$ cd ; pwd
/home/sachin
/home/sachin
$
$


Linux : File Systems : cd
cd .. : cd to parent directory cd - : cd to previous working
directory

Example :
Example:
$ cd ~ ; pwd
$ cd /z/y/x/w/v/u; pwd
/home/sachin
/z/y/x/w/v/u
$ cd .. ; pwd
$ cd /a/b/c/d/e/f; pwd
/home
/a/b/c/d/e/f
$
$ cd -; pwd
/z/y/x/w/v/u
$

Linux : File Systems : mkdir
mkdir : make directories Example :
$ cd $HOME
Options : $ mkdir lab
-p : no error if it already $ mkdir lab
exists, make parent
mkdir: cannot create directory
directories as needed
`lab': File exists
$ mkdir -p lab
Usage :
$ mkdir -p lab/scratch
$mkdir <dirname>


Linux : File Systems : cat
cat – concatenate files and print on the standard output
Usage:
$ cat <list of files>

Example:
$ cat /etc/issue
Fedora release 14 (Laughlin)
Kernel r on an m (l)

$

Linux : File Systems : head
head – output the first part of files
The head command without any argument displays first 10 lines of
a file.
Usage:
$ head <filename>

Example: To display first two lines
$ head -2 /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
$

Linux : File Systems : tail
tail – output the last part of files
The tail command without any argument displays last 10 lines of a
file.
Usage:
$ tail <filename>

Example: To display last two lines
$ tail -2 /etc/passwd
oracle:x:501:501::/usr/lib/oracle/xe:/bin/bash
tomcat:x:91:91:Apache Tomcat:/usr/share/tomcat6:/sbin/nologin
$

Linux : File Systems : more
more : paging through text one screenful at a time.
The command also shows % of text already covered at bottom.
Usage:
$ more <filename>
Commands:
To quit – press q
To go to next page – press space bar
To go to prev page for files (not for pipes) – press b
Example:
$ more /etc/httpd/conf/httpd.conf
$

Linux : File Systems : less
less : similar to more.
Less allows backward movement in the file as well as forward
movement
Usage:
$ less <filename>

Commands:
To quit – press q
To go to prev/next page – press page up/down
Example:
$ less /etc/httpd/conf/httpd.conf
$

Linux : File Systems : touch
touch – create a zero size file / change time stamp
Creates a zero size file if the file doesn't exist.
Change modification time if the file already exists.
Usage:
$ touch <filename>

Example:
$ cd ~/lab/scratch
$ touch touch.txt
$ cat touch.txt
$ www.opengurukul.com 17

Linux : File Systems : echo
echo – display text to standard output

Usage:
$ echo <text>

Example:
$ cd ~/lab/scratch
$ echo “Hello World”
Hello World

Linux : File Systems : ls
ls - list directory contents
Options:
-a show entries starting with dot (.) and dot dot (..)
-l show long listing format
-t sort by modification time
-r reverse the order
Example:
$ cd /home
$ ls
sachin surikuma root ksurinde laxmi yukta kumasuri sunil saurav

Linux : File Systems : ls -a
ls -a : do not ignore entries starting with dot
Example :
$ cd ~/lab/scratch
$ touch .system.txt
$ ls
echo.txt touch.txt
$ ls -a
.system.txt echo.txt touch.txt
$


Linux : File Systems : ls -l
ls -l : use a long listing format
<file type> <permissions> <link count> <file owner> <group of
owner> <file size> <date of modification> <time of modification>
<file name>
Example :
$ cd /bin
$ ls -l *sh*
-rwxr-xr-x. 1 root root 877480 Jun 22 2010 bash
-rwxr-xr-x. 1 root root 102408 Jun 21 2010 dash
lrwxrwxrwx. 1 root root 4 Jan 27 2011 sh -> bash
-rwxr-xr-x 1 root root 597768 Mar 22 2010 zsh

$

Linux : File Systems : ls -t
ls -t : sort by modification time

Example :
$ cd /bin
$ ls -lt *sh*
$

Linux : File Systems : ls -r
ls -r : reverse order while sorting

Example :
$ cd /bin
$ ls -ltr *sh*
$

Linux : File Systems : ln
ln : create hard/soft links between files
Soft Link (Symbolic Link):
The symbolic link contain path of the target link.
The symbolic link can cross boundaries of file systems.
Hard Link:
Hard links are supported within a file system and these are
used to refer to an existing content by some other name
within the same file system.
The inode number will be same for hard links.
Most of the file systems do not support hard linking directories.


Linux : File Systems : ln & ln -s
Usage: Example :
$ ln -s <old path> <new_name> Symbolic Link (ln -s):
-s : create a symbolic link $ cd /bin
without -s : creates a hard link $ ln -s bash sh
$
NOTE :
On AIX, /bin/sh is a hard linked Hard Link (ln):
to /bin/ksh.
$ cd /bin
On Linux, /bin/sh is a soft link
$ ln ksh sh
to /bin/bash.
$

Linux : File Systems : soft link

Example :
$ ls -l /bin | grep -e ^l | grep -e vi
lrwxrwxrwx. 1 root root 2 Jan 27 2011 ex -> vi
lrwxrwxrwx. 1 root root 2 Jan 27 2011 rvi -> vi
lrwxrwxrwx. 1 root root 2 Jan 27 2011 rview -> vi
lrwxrwxrwx. 1 root root 2 Jan 27 2011 view -> vi
$


Linux : File Systems : cp
cp: copy files and directories

SYNOPSIS :
cp SOURCE DEST
cp SOURCE... DIRECTORY
Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY

Option :
-R copy directories recursively (otherwise directories will be
omitted)

Linux : File Systems : cp
cp: copy files and directories

Example :
$ cp ~/.bashrc ~/.bashrc.orig
$ cp /etc/profile.d ~/
cp: omitting directory `/etc/profile.d'
$ cp -R /etc/profile.d ~/
$


Linux : File Systems : mv
mv: move (rename) files
SYNOPSIS :
mv [OPTION]... SOURCE DEST
mv [OPTION]... SOURCE... DIRECTORY
DESCRIPTION
Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY
Example:
$ cp ~/.bashrc /tmp
$ mv /tmp/.bashrc /tmp/.bashrc.new
$ ls /tmp/.bashrc*
/tmp/.bashrc.new www.opengurukul.com 29

$

Linux : File Systems : rm
rm : remove files or directories

SYNOPSIS:
rm [OPTION]... FILE...

Options:
-i : interactive (prompt before every removal)
-f : ignore nonexistent files, never prompt (force)
-r : remove directories and their contents recursively


Linux : File Systems : rm
example
Example (rm) :
$ cd /tmp
$ touch rm1.out
$ rm rm1.out
$ ls rm1.out
ls: cannot access rm1.out: No such file or directory
$


Linux : File Systems : rm -i
Example (rm -i) :

$ cd /tmp
$ touch rm2.out
$ rm -i rm2.out
rm: remove regular file 'rm2.out'? Y
$ ls rm2.out
ls: cannot access rm2.out: No such file or directory
$


Linux : File Systems : rm -f
Example (rm -f) :

$ rm non_existent_file.txt
rm: cannot remove `non_existent_file.txt': No such file or directory
$ rm -f non_existent_file.txt
$


Linux : File Systems : rm -r
Example (rm -r) :

$ cd /tmp
$ mkdir scratch
$ rm scratch
rm: cannot remove `scratch/': Is a directory
$ rm -rf scratch
$


LINUX

MODULE : VI – Text Editor


LINUX: VI Editor
To invoke
Type vi or 'vi filename'.
To come out of vi editor
Use ESC (get into command mode), followed by : (ex
editor mode), followed by q (quit) and then press
ENTER.
$ vi
Hi I am Open Gurukul
:q

LINUX: VI Editor : Mode

The VI editor run in 3 different modes

INSERT mode

COMMAND mode

ED/EX Editor mode


LINUX: VI Editor : Command
Mode
Command mode
Use ESC to go to COMMAND mode anytime.
The typed character will not be visible in COMMAND
mode.
Under COMMAND mode, each character has special
significance and the designated action takes place.


LINUX: VI Editor : INSERT Mode
INSERT mode
The characters typed are visible when the editor is in
INSERT mode.
To get into INSERT mode from command mode
i – insert
shift+a – insert at end of line


LINUX: VI Editor : EX Mode
ED/EX Editor mode
The ED/EX editor commands are typed after typing ':'
in command mode.
From INSERT mode, we can use ESC + ':' to get into
ED/EX mode.


LINUX: VI Editor : Commands
INSERT
i – insert
shift+a – append at end of line
DELETE
x – delete a single character
dw – delete a word
dd – delete a line


LINUX: VI Editor : Commands
Undo / Redo
u – undo the last commands action
. (dot) – redo the last commands action
Repeat Action
<repeat_count>command
5dd – deletes 5 lines


LINUX: VI Editor :Ex :Save & Quit
:w
write contents to a file
:w /tmp/1.out
write contents to file /tmp/1.out
:q
quit (will not work if there were changes after last write)
:wq
write and quit
:q!
quit (ignore recent modifications)

LINUX: VI Editor : Copy & Paste
yy – yank line into buffer
<number_of_lines>yy – yank multiples lines into buffer
(2yy – yank 2 lines into buffer)
Go to line where the content of buffer has to be pasted.
Type p to print contents of buffer


LINUX: VI Editor: Search Pattern
/pattern
To goto a line that matches pattern.
?pattern
To go to a line that matches pattern in the reverse
direction.
n
Go to next such pattern match.
N (shift+n)
Go to next such pattern match in reverse direction.
:set ic
To ignore case while searching, set ic.

LINUX: VI Editor: Line Numbers
Display Line Numbers
:set nu # To display line numbers
Do not Display Line Numbers
:set nonu # To stop displaying line numbers
To goto a particular line
:1 # first line in the file
:$ # last line in the file
:line_num # Goto line number line_num


LINUX: VI Editor: Search &
Replace
To replace old pattern with the new pattern in entire file.
:1,$s/old/new/g
replace old with new in entire file from first line to last
line.
:.,+50s/old/new/g
replace old with new in file from current line (.) to next
50 lines


LINUX: VI Editor: Editor Options
To see options that are currently set.
:set
To see all the options
:set all


LINUX: VI Editor: Multiple Files
To operate on multiple files, specify all of them
while invoking vi editor.

$ vi /tmp/1.txt /tmp/2.txt

:files # to see files opened by vi editor
:n # to go to next files
:rew # to rewind to the first file

LINUX

Module : Environment


Linux : Environment : printenv
printenv : print all or part of environment
Usage:
printenv
Example:
$ printenv | grep -e HOME -e PWD -e SHELL -e USER -e HOSTNAME
HOSTNAME=sachin-pc
SHELL=/bin/bash
OLDPWD=/tmp
USER=sachin
PWD=/home/sachin/lab/linux/scratch
HOME=/home/sachin

Linux : Environment : export
export: exports an environment variable
To set an environment variable so that it is visible to even child
processes.
Example :
$ export MY_NAME=sachin1
$ echo $MY_NAME

To set an environment variable
$ MY_NAME=sachin1 (It will not be visible to child processes.)
$ echo $MY_NAME

LINUX : Environment : PS1
PS1 : stores value of primary prompt

Example :

$ export PS1='c: > ' # change the prompt
c: > export PS1='$' # revert the prompt
$


LINUX : Environment : PS2
PS2
Stores value of secondary prompt.
Used when the command line is incomplete.
Default secondary prompt is '>'.

Example :

$ echo 'hello
>'

Linux : Environment: HOME and
PATH
HOME : stores home directory of user.
$ echo $HOME
/home/sachin
$
PATH : stores list of directories that should be searched for
the executable if the absolute/relative path of an
executable has not been specified.
$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin
$

Linux : Environment: PWD &
OLDPWD
PWD : has value of current working directory.
$ cd /tmp
$ echo $PWD
/tmp
$
OLDPWD : has value of last working directory
$ cd /var; cd /tmp
$ echo $OLDPWD
/var
$
NOTE :
The value of OLDPWD is used by command “cd -” to go back to last working
directory

Linux : Environment: SHELL, HOSTNAME, USER

SHELL : To know path of SHELL program.
$ echo $SHELL
/bin/bash
$
HOSTNAME : To know host name
$ echo $HOSTNAME
sachin-pc
$
USER : Name of User logged in.
$ echo $USER
sachin www.opengurukul.com 58

$

Linux: Environment: BASH Files
/etc/profile : system wide initialization file
It is executed for login shells.
$HOME/.bash_profile : personal initialization file
It is executed for login shells.
$HOME/.bash_logout : individual login shell cleanup file
It is executed when a login shell exits.
$HOME/.bash_history : command history list file
It stores commands executed by us.


Linux: Environment: History
history : display the command history list with line numbers
The history command displays the command history list with line numbers.
$ history
1037 cd /var; cd /tmp;
1038 echo $OLDPWD
$
Execute a command from history :
$ !1037 # to execute 1037th command.
HISTSIZE : number of commands to be stored in history file
$ echo $HISTSIZE
1000

Linux

Module : FILE ACCESS


Linux: File Access: whoami
whoami : print effective user id
$ whoami
sachin
$
groups : print the groups a user is in
$ groups
sachin
$

Linux: File Access: id & chmod
id : print user identity
$ id
uid=500(surikuma) gid=500(surikuma) groups=500(surikuma)
$
chmod : change file mod bits


Linux: File Access: file type

<filetype> <rwx perm for owner> <rwx perm for group> <rwx
perm for others>

Regular file : '-'
Directory : 'd'
Pipes : 'p'
Character device special files : 'c'
Block device special files : 'b'
For symbolic links : 'l'
For sockets : 's'


Linux: File Access: chmod

User / Group / Other Read / Write / Execute
r(read)
u (user)
w(write)
g (group) x(execute)
o (other)
Octal Numbers for R / W / X
4 – read
2 – write
1 - execute (file) / search
(directory)

Permissions Calculations Octal Number
RWX 4+2+1 7
RW- 4+2 6
R-X 4+1 5
R-- 4 4
-WX 2+1 3
-W- 2 2
--X 1 1


To give all the permissions to everybody on a file/directory
$ chmod 777 path
$

To give execute permission on a file
$ chmod +x path
$

To give execute permission on a file to user alone
$ chmod u+x path
$

Linux: File Access: umask
umask : unix mask
$ umask
022
$
Initial permission for
new file : 666 - umask
new directory : 777 - umask
NOTE :
On Linux, umask is 002 in case user name and group
name are same. www.opengurukul.com 68

Linux: File Access: chown
chown : change file owner & group

The -R option is used to change the ownership
recursively.

$ chown -R <username>:<group name> <path>


Linux

MODULE :
Filters (wc, grep, sed, awk, sort)


Linux: Filters: wc
wc : print newline, word, and byte counts for each file
$ wc /etc/passwd
56 98 2916 /etc/passwd
$
wc -l : print the newline counts
$ wc -l /etc/passwd
56 /etc/passwd
$

NOTE:
The wc stands for wordcount.

Linux: Filters : wc
wc -w : print the word counts
$ wc -w /etc/passwd
98 /etc/passwd
$

wc -c : print the byte counts
$ wc -c /etc/passwd
2916 /etc/passwd
$


Linux: Filters: grep
grep : print lines matching a pattern

Syntax :
grep [OPTIONS] PATTERN [FILE...]

Example :
$ grep root /etc/passwd
operator:x:11:0:operator:/root:/sbin/nologin
$

Linux: Filters: grep -e & -E
grep -e PATTERN : use PATTERN for search
$ grep -e sync -e shutdown /etc/passwd
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
$
grep -E PATTERN : egrep - use extended PATTERN for
search
$ grep -E 'sync|halt' /etc/passwd
halt:x:7:0:halt:/sbin:/sbin/halt
$

Linux: Filters: grep -f
grep -f file : patterns are kept in file
$ cat /tmp/patterns.txt
sync
halt
$ grep -f /tmp/patterns.txt /etc/passwd
$

Linux: Filters: grep -v
grep -v : Invert the sense of matching, to select non-
matching lines

$ cat /etc/passwd | grep -v nologin | grep -v bash
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
jetty:x:490:481::/usr/share/jetty:/bin/sh
$


Linux: Filters: grep -n
grep -n : Prefix each line of output with the line number
within its input file

$ grep -n -e halt -e sync -e shutdown /etc/passwd
6:sync:x:5:0:sync:/sbin:/bin/sync
7:shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
8:halt:x:7:0:halt:/sbin:/sbin/halt
$


Linux: Filters: grep -i
grep -i : Ignore case distinctions in both the PATTERN
and the input files

$ grep ROOT /etc/passwd
$ grep -i ROOT /etc/passwd
operator:x:11:0:operator:/root:/sbin/nologin
$


Linux: Filters: sort
sort : sort lines of text Example :
files

$ sort lamp.txt
$ cat lamp.txt lang: php, perl, python
os: linux os: linux
webserver: apache rdbms: mysql
rdbms: mysql webserver: apache
lang: php, perl, python $

Linux: Filters: sort -n
sort -n : compare $ sort sort.txt
according to string 10
numerical value 2
$

$ cat sort.txt $ sort -n sort.txt
2
2 10
$
10
$

Linux: Filters: sort -u
sort -u : unique records $ sort sort_u.txt
The uniq command also hello
select unique adjacent lines.
hello
The uniq command is also
dependent on sort command HELLO
to sort the records.
HELLO
$ cat hello.txt $
HELLO
hello $ sort -u sort_u.txt

HELLO hello

hello HELLO

$ $

Linux: Filters: sort -r
sort -r : reverse the result Example :
of comparisons

$ sort -r lamp.txt
$ cat lamp.txt
webserver: apache
os: linux
rdbms: mysql
webserver: apache
os: linux
rdbms: mysql
lang: php, perl, python
lang: php, perl, python
$
$

Linux: Filters: sed
sed – stream editor
used for search and replace operation on a file.

Syntax :
sed -e 's/old pattern/new word/gi' file

/g is to replace globally. Multiple patterns on the
same line will be replaced.
/i is to ignore care while matching pattern

Linux: Filters: sed -e
Example: Example:

$ sed -e 's/mysql/oracle/gi' $ sed -e 's/mysql/oracle/gi'
lamp.txt -e 's/php/perl/gi' lamp.txt
os: linux os: linux
lang: php, perl, python lang: perl, perl, python
rdbms: oracle rdbms: oracle
webserver: apache webserver: apache
$ $


Linux: Filters: awk
awk - pattern scanning and AWK Variables :
processing language
$0 – current record
awk is mainly used for
$1 – first field of current
selecting fields from the
record
output.
$2 – second field of current
Syntax :
record
awk -Ffs ' /pattern/ {action}'
...
Option :
$NF – last field of C.R.
-F is used to specify field
NF – number of fields in C.
separator (default is white
R.
space)
NR – number of records read
so far

Linux: Filters: awk example
Example :
To display first and last entry for root user.
$ awk -F: ' /^root/ { printf("%s %sn",$1, $NF); } ' /etc/passwd
root /bin/bash
$


Linux

MODULE : PROCESS


Linux: Process: ps
ps : report a snapshot of the current processes

It displays PID(process id), TTY(terminal), and CMD(command) of
existing processes.

Example :
$ ps
PID TTY TIME CMD
17286 pts/0 00:00:00 bash
$

Linux: Process: ps -e
ps -e : to see all the processes

Example :
$ ps -e | head -3
PID TTY TIME CMD
1? 00:00:01 init
2? 00:00:00 kthreadd
$

NOTE :
-e is equivalent to -A.

Linux: Process: ps -f
ps -f : does full-format listing
It can be combined with any other option.
It displays uid (user id), pid (process id), ppid (parent process id),
c (nice value), stime (start time), tty, time executed and cmd.

Example:

$ ps -ef | head -2
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 09:12 ? 00:00:01 /sbin/init

Linux: Process: jobs
jobs : List active jobs
If a programs takes more time during execution, it can be put into
background by using & at the end in the command line.
The process which is either running in the background or is in the
stopped state is shown in the jobs.
Example:
$ sleep 60 &
[1] 12721
$ jobs
[1]+ Running sleep 60 &
$

Linux: process: fg & bg
fg : run job in the foreground
To bring the process from background to foreground (terminal),
use fg command.
Example:
$ fg %job_number

bg : run job in the background
To run a suspended job in the background use bg command.
Example:
$ bg %job_number

Linux: process: ^Z & kill
CONTROL+Z : to suspend a kill : send a signal to job
process
To stop a foreground process,
Example:
use CONTROL+Z.
$ kill %job_number
Example:
$ sleep 60
NOTE:
^Z
It will send SIGTERM(15) to job
[1]+ Stopped sleep 60
number.
$ jobs
[1]+ Stopped sleep 60
$

Linux: Process: jobs example
$ sleep 60 & $ jobs
[1] 12721 [1]+ Stopped sleep 60
$ jobs $ bg %1
[1]+ Running sleep 60 & [1]+ sleep 60 &
$ fg %1 $ jobs
sleep 60 [1]+ Running sleep 60 &
^Z $ kill %1
[1]+ Stopped sleep 60 [1]+ Terminated sleep 60
$ $ jobs
$

Linux: process: kill
kill: signal a process
To send a signal to a process, kill command is used.
Example :
$ kill -<signal_number> <PID>
The signal number 9 is for SIGKILL.
$ kill -9 $$ # will send SIGKILL(9) to your shell program
$ kill <pid> # will send SIGTERM (15) to the pid.
$ kill -l # to see list of signals
NOTE :
Signal SIGKILL cannot be masked. Used to kill the process.

Linux: process: kill -l
$ kill -l
1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL 5) SIGTRAP
6) SIGABRT 7) SIGBUS 8) SIGFPE 9) SIGKILL 10) SIGUSR1
11) SIGSEGV 12) SIGUSR2 13) SIGPIPE 14) SIGALRM 15)
SIGTERM
16) SIGSTKFLT 17) SIGCHLD 18) SIGCONT 19) SIGSTOP
20) SIGTSTP
21) SIGTTIN 22) SIGTTOU 23) SIGURG 24) SIGXCPU 25)
SIGXFSZ
26) SIGVTALRM 27) SIGPROF 28) SIGWINCH 29) SIGIO 30)
SIGPWR
31) SIGSYS 34) SIGRTMIN ....64) SIGRTMAX
$

Linux : processes: nohup
nohup : run a command immune to hangups, with output
to a non-tty

Syntax:
nohup command

NOTE:
Sends the output to 'nohup.out' or '$HOME/nohup.out'.


Linux

MODULE : DISK


Linux: disk: fdisk
fdisk: Create & Edit Partition Table.
Example:To print partition table
$ fdisk /dev/sda
Command (m for help): p
Disk /dev/sda: 120.0 GB, 120034123776 bytes
255 heads, 63 sectors/track, 14593 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x3db20996
Device Boot Start End Blocks Id System
/dev/sda1 * 1 25 200781 83 Linux
/dev/sda2 26 14593 117017460 8e Linux LVM
Command (m for help): q www.opengurukul.com 99

Linux: disk : mkfs
mkfs : build a file system
To create file system on partition (logical volume)
Example:
$ mkfs /dev/hda2
$
/etc/fstab : file system table
The file system table that maps partitions to be mounted and the directory on
which it has to be mounted.
Example:
$ cat /etc/fstab
# partition mount-directory fs-type mount-options dump fsck-order
/dev/sda1 / ext4 defaults 1 1
$

Linux: disk : mount & unmount
mount : mount a file system
Mount file systems on partitions (logical volumes) to directories.
Example:
$ mount /dev/cdrom /mnt/cdimage
$

umount : unmount a file system
Unmount a file system from directory
Example:
$ umount <mounted dir name> # dirname on which fs has been mounted.
$ umount /dev/cdrom # or umount /mnt/cdimage

Linux: disk : du
du : estimate file space usage
To check disk used @ directory level.
Options :
-s summary (do not display for each directory)
-h print sizes in human readable format (e.g., 1K 234M 2G)


Linux: disk : du example

$ du -sh /etc/rc.d
596K /etc/rc.d
$


Linux: disk : df
df : report file system disk space usage
To check free space on a partition (logical volume)
Options :
-h in human readable format
Usage :
$ df # see all mounted file systems
or
$ df <mounted directory name>


Linux: disk : df example
$ df -h
Filesystem Size Used Available Use% Mounted on
/dev/mapper/VolGroup00-rootlv 77G 23G 51G 31% /
/dev/sda1 190M 47M 134M 26% /boot
/dev/mapper/VolGroup00-datalv 29G 22G 6.1G 78% /data
$
$ df -h /home
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-rootlv 77G 23G 51G 31% /
$


LINUX

MODULE : NETWORK


Linux: Network: ifconfig
ifconfig : configures a network interface
Used to configure a network interface.
Also used to retrieve configuration of network interface like ip address of
the Ethernet network interface 'eth0'.
Option:
-a show all interfaces
Example:
To know ip address of Ethernet network interface eth0.
$ /sbin/ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:21:70:B1:3F:01
inet addr:192.168.1.35 Bcast:192.168.3.255 Mask:255.255.252.0
$

Linux: Network: ssh
ssh : remote login program
The ssh is a remote login program like telnet to operate on remote
machine.

Syntax:
$ ssh -l login_name host_name

Example:
$ ssh -l matsya1 192.168.1.2
$

Linux: Network: ftp
ftp: Internet file transfer program
To get/put files from/to internet.
Example :
$ ftp <remote_hostname>
Username :
Password :
ftp> cd <remote_directory_name>
ftp> lcd <local_directory_name>
ftp> pwd <remote directory name>
ftp> ! pwd <local directory name>

Linux: Network: ftp : example
ftp> get file # to get single file from remote host to current box
ftp> put file # to put single file from current box to remote box
ftp> mget file* # to get files from remote host to current box
ftp> mput file* # to put files from current box to remote box
ftp> prompt # to disable prompt
ftp> bi # binary mode
ftp> ha # hash
ftp> bye


LINUX

MODULE : COMMANDS


Linux: Commands : locate
locate : find files by name
The locate reads one or more databases prepared by
updatedb and writes file names matching at least one of
the PATTERNs to standard output, one per line.
Example :
$ locate php.conf
/etc/httpd/conf.d/php.conf
$
NOTE:
The database for locate is prepared by updatedb.

Linux: Commands : updatedb.conf
updatedb.conf : Do not index following file system types, names, paths.
$ cat /etc/updatedb.conf
PRUNE_BIND_MOUNTS = "yes"
PRUNEFS = "9p afs anon_inodefs auto autofs bdev binfmt_misc cgroup
cifs coda configfs cpuset debugfs devpts ecryptfs exofs fuse fusectl
gfs gfs2 hugetlbfs inotifyfs iso9660 jffs2 lustre mqueue ncpfs nfs nfs4
nfsd pipefs proc ramfs rootfs rpc_pipefs securityfs selinuxfs sfs sockfs
sysfs tmpfs ubifs udf usbfs"
PRUNENAMES = ".git .hg .svn"
PRUNEPATHS = "/afs /media /net /sfs /tmp /udev /var/cache/ccache
/var/spool/cups /var/spool/squid /var/tmp"
$

Linux: Commands : find
find – search for files in a directory hierarchy
find <STARTING DIRECTORY> <OPTIONS> <EXPRESSION>
Options :
–name : search for files matching a pattern
–type : search for files of a particular type ('f' is for regular file and
'd' is for directory)
–exec : execute an action if the file is found
Example :
$ find /etc -name 'httpd.conf' -type f -exec ls -l {} ;
-rw-r--r--. 1 root root 34417 Jul 9 2010 /etc/httpd/conf/httpd.conf

Linux: Commands: uname
uname -s : os name uname -n : node name
$ uname -s $ uname -n
Linux sachin-pc
$ $

uname : os, host, kernel & arch information
$ uname -a
Linux sachin-pc 2.6.27.9-73.fc9.i686 #1 SMP Tue Dec 16
15:25:05 EST 2008 i686 i686 i386
GNU/Linux

Linux: Commands: su
su - run a shell with substitute user and group IDs
This command is used to switch user.
To become a super user, su can be used without arguments or (su root)


Linux: Commands: su : Example
$ id
uid=500(surikuma) gid=500(surikuma) groups=500(surikuma),501(dba)
$ su # without any argument, ask for root password
Password:
# id
uid=0(root) gid=0(root)
groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),501
(dba)
# su surikuma # root can switch to any user
$ id
uid=500(surikuma) gid=500(surikuma) groups=500(surikuma),501(dba)

Linux: Commands: date
date - print or set the system date and time

Syntax : Get Date
$ date
Sat Sep 19 22:43:14 IST 2009
$

Syntax : Set Date
$ date [MMDDhhmm[[CC]YY][.ss]


Linux: Commands: cal
cal : displays calendar
The cal displays calendar for current month without any args

Options:
-1 : displays calendar for current month
-3 : displays calendar for previous/current/next month
-y : displays calendar for current year


Linux: Commands: cal example
Example :
$ cal
October 2011
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31 www.opengurukul.com 120

UNIX

MODULE : Fedora & OpenSuse : .rpm
packages : rpm and yum


Linux: rpm : -e & -i

rpm -i : install package
$ rpm -i <package_name.rpm>
$

rpm -e : erase/delete package
$ rpm -e <package_name>
$


Linux: rpm: package contents
rpm -q -a : list all packages installed on systems
$ rpm -qa | grep -e '^httpd'
httpd-tools-2.2.16-1.fc14.i686
httpd-2.2.16-1.fc14.i686
httpd-manual-2.2.16-1.fc14.noarch
$


Linux: rpm -q -list -p
rpm -q –list : list files included in an installed rpm package
$ rpm -q –list <package_name>
$ rpm -q --list php
/usr/lib/httpd/modules/libphp5.so
/var/lib/php/session
/var/www/icons/php.gif
$
rpm -q –list -p : list files included in an rpm package
$ rpm -q –list -p <package_location>
$ rpm -q --list -p /var/cache/yum/updates-newkey/packages/*.rpm

$

Linux: rpm: -q -f
rpm -q -f <filename> : Find the Package that Contains a file.
$ rpm -qf /etc/issue
fedora-release-14-1.noarch
$


Linux: yum
yum : Install/update packages directly from internet
You must be a super user to install package directly from
internet.
You can create/update repositories information in
/etc/yum/repos.d/


UNIX

MODULE : Debin / Ubuntu LINUX : .deb
packages : dpkg and apt-get


Linux: dpkg : -i & -r

dpkg -i : install package
$ dpkg -i <package_name.deb>
$

dpkg -r : remove package
$ dpkg -r <package_name>
$


Linux: dpkg : package contents
dpkg -l : list all packages installed on systems
$ dpkg -l | grep -e 'apache'
$

The second filed has the package name.


Linux: dpkg -c & -L
dpkg -L : list files included in an installed package
$ dpkg -L <package_name>
$ dpkg -L php
/usr/lib/httpd/modules/libphp5.so
/var/lib/php/session
/var/www/icons/php.gif
$
dpkg -c <.deb pkg name>: list files included in a deb package
$ dpkg -c <deb_package_location>

Linux: dpkg : -S
dpkg -S <filename> : Find the Package that Contains a file.

$ dpkg -S /bin/ls
coreutils: /bin/ls
$


Linux: apt-get
apt-get : Install/update packages directly from internet
You must be a super user to install package directly from
internet.
You can create/update repositories information in
/etc/apt/sources.list


Linux : apt-get : list, update,
install, remove
yum list: list packages apt-get install: install package
$ yum list <package_name>* $ apt-get install <package_name>
$ $
To list packages matching bluefish To install bluefish editor
$ yum list *bluefish* $ apt-get install bluefish

apt-get update: update package apt-get remove: remove package
$ apt-get update <package_name> $ apt-get remove <package_name>
$ apt-get update bluefish $
To remove bluefish editor
$ apt-get erase bluefish

UNIX

MODULE : LINUX


Linux : Distribution Info
/etc/*release - distribution name & version

$ ls /etc/*release
/etc/fedora-release /etc/redhat-release /etc/system-release
$ cat /etc/*release
$

Linux : LSB Distribution Info
lsb_release – Distribution Information using LSB

$ lsb_release -a
LSB Version: :core-4.0-ia32:core-4.0-noarch
Distributor ID: Fedora
Description:Fedora release 14 (Laughlin)
Release: 14
Codename: Laughlin
$

Linux: Services
Service : status, start, stop, restart
$ service <service_name> status | start | stop | restart

Example:
$ service httpd status # status of apache web server
# service httpd start # start apache web server
# service httpd restart # restart apache web server
# service httpd stop # stop apache web server


Linux: gzip & gunzip
gunzip/gzip : GNU unzip/zip

To zip a file using GZIP.
$ gzip x.tar (creates x.tar.gz)
$

To unzip a file using GUNZIP.
$ gunzip x.tar.gz (creates uncompressed x.tar file)
$


Linux: bzip2 & bunzip2

bzip2/bunzip2 - block-sorting file compressor
The block-sorting file compressor - better than GNU
zip/unzip.

bzip2: To zip a file
$ bzip2 x.tar (creates x.tar.bz2)
$

bunzip2 : To unzip a file
$ bunzip2 x.tar.bz2 (creates uncompressed x.tar file)
$

Linux: tar
tar : tape archive commands
The tape archive is used to combine multiple files and
directories into one file.
Options :
-v verbose mode
-f target file
-c create tar
-t list toc of tar
-x extract files from tar


Linux: tar : -c
tar -c : create a tar file Example :
Syntax : $ cd /tmp
tar -c -v -f <tar file> <list of $ tar -cvf team.tar team
files>
$ tar -cvf /tmp/team.tar team
Setup :
team/
$ cd /tmp
team/india/
$ mkdir -p team/india
team/india/sachin
$ mkdir -p team/australia
team/australia/
$ touch team/india/sachin
team/australia/ricky
$ touch team/australia/ricky
$

Linux: tar : -t
tar -t : list table of contents
Syntax :
tar -t -v -f <tar_file>
Example :
$ tar -t -v -f /tmp/team.tar
drwxrwxr-x sachin/sachin 0 2011-10-03 23:47 team/
drwxrwxr-x sachin/sachin 0 2011-10-03 23:47 team/india/
-rw-rw-r-- sachin/sachin 0 2011-10-03 23:47 team/india/sachin
drwxrwxr-x sachin/sachin 0 2011-10-03 23:47 team/australia/
-rw-rw-r-- sachin/sachin 0 2011-10-03 23:47 team/australia/ricky
$

Linux: tar : -x
tar -x : extract files from a tar Example :
file
$ cd /tmp
To extract all the files
$ mkdir -p new; cd new
$ tar -xvf <tar file>
$ tar -xvf /tmp/team.tar
$
team/
To extract a particular file/dir
team/india/
$ tar -xvf <tar file> <file path>
team/india/sachin
$
team/australia/
team/australia/ricky
$

Linux: install s/w from sources
Steps : Steps :
Download .tar.bz2 file or .tar.gz. $ bunzip2 software.tar.bz2
Unzip and Extract $ tar -xvf software.tar
Configure $ cd software
Create Makefile $ ./configure
Run Make $ make clean
Install using Make $ make all
$ make install


Linux: Support

Please register yourself
@
www.opengurukul.com
In case you need any support in future.


OpenGurukul : Operating System : Linux

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