Tuesday, 7 May 2013

Basic Unix Commands

1) login to the unix/solaris server
 username: cts
 passwd : *******

You will log in to the server. It will take you to default home_directory.

2) pwd
it shows/prints the present working directory



3)ls -l
gives listing of the files in present directory

4) cd ..
takes you to previous directory

5)mkdir <directory>
will create directory

6) mkdir -p /home/jb/j1/j2/j3
will create all the non-existing directories at a stretch

7)vi <file_name>
opens file for reading/editing
8)cat <file_name>
display contents of file
9)more <file_name>
displays page by page contents of file
10) tail <file_name>
shows last 10 lines of file

use tail -f for continous update of file_name
head <file_name>
shows first 10 lines of file_name

11) touch <file_name>
creates a zero/dummy file

12)ln file1 file2
creates link of file1 to file2

13) file <file_name>
shows what type of file it is like
$ file *
acrawley.html:  ascii text
admin:          directory
afiedt.buf:     ascii text
autosys_env_IBKNYR1:    commands text


14) cd /home/<directory_name>
takes you to /home/<directory_name> directory
likewise you can give and directory
Note: remember to give from the beginning like '/' is very important. Its called the root directory. In Unix/solaris/<any_falvor_of_unix> path is specified from the root i.e., '/'
If you have root privileges you can go to any directory.
For normal users its not possible.

15)clear
clears the screen


16) cd /usr/bin
this directory has all the commands of unix. you can say ls -l or ls for listing all the commands in that directory and can try executing each of the commands.
if u have any doubt on any command just say "man <command_name> like if you want to know what ls command will do give "man ls", it displays man page.

Similarly /usr/sbin has administrative related commands
/usr/lib has libraries
and

/etc consists of system administrative and tuning files
17)who
will display which users are logged into system.
18)$w
will  display more info abt the users logged in
19)once you login to the system your home directory will be set. in between if you navigate/go to other directories and after that if you give "cd " it will take you back to your home direcory.
20) ps -ef
shows process status of various active processes.(use more/other options to get more info)
21) rm <file_name>
will delete file specified

22)rm *
will delete all the files in the present directory (BE CAREFUL WHILE GIVING THIS COMMAND)
23) grep <pattern> file_name
checks pattern/word in file name specified
24) chmod 777 <file_name>
changes file_name/directory permissions
chmod -R 777 /<directory_name>
changes permissions recursively all the files and direcories under parent directory

25) chown owner:group <file_name>
changes owner and group for the file_name

Similarly  chown -R owner:group /<directory>
changes ownership/group recursively all the files and direcories under parent directory

26)rsh <server_name>
rsh -l <login_name> <server_name>
rcp file1 file2

accessing remote servers (This requires pre-configuration on remote servers like .rhosts and hosts.equiv)
27) gunzip <file_name>
unzips file name

gzip <file_name>
zips file_name

compress <file_name>
compresses file_name  (gzip/compress uses different algorithm for (compression)

uncompress <file_name>
uncompresses file_name

pack <file_name>
unpack <file_name>

packs/unpacks file_name
All the above can be used on directory for compression
28) which <file_name>
shows if the file_name/command exists and if exists where its path is

29)bc -l
bench calculator

30)ulimit
shows the size of file, time, memory etc available for current shell

31)man <command_name>
gives help/man pages of command given

32)write <user_name>
you can write messages to the logged in users on the server

33)wall
this command writes/sends messages to all users logged in (useful while shutting down m/c)

34)fuser -k /dev/pts/2
kills terminal pts/2 and closes its connection
35)nohup <command_name> &
nohup is very useful command. it runs the command even the telnet connection is closed/broken.
& is used for running command in background.

36)crontab -l
shows the cron jobs running/scheduled for the current user.
you can copy/redirect the jobs to a ascii file and edit/add jobs and resubmit to cron as

-->$crontab -l > present_cronjobs
-->edit/add entries to present_cronjobs
-->$crontab present_cronjobs  (This will submit/resubmit the jobs in file presnt_cronjobs to CRON)

37)at
at is very useful command for running jobs at later time
like
at <time> command/script (will run the script at specified time)

at -l will show the at jobs scheduled
38)killing an unwanted process
$ps -ef|grep <process_name> (will show the PID of the process in the 2nd field)
$kill -9 <PID>

39)who -b
shows when the system has booted
40)$uptime
will show how long the system has been up and also shows cpu load, number of users logged in etc.
41)last
will show the users logged in/out information
last <user_name>  shows particular user logins/logouts
last reboot  shows all the system boots


42)id
shows current user's UID, username and GID and group name

43)hostid
shows unique identifier of host
44) more /etc/passwd
it will show all the logins, home directories of the users.
45) more /etc/shadow
shows password encryption info and other user related info (only root has access to this file)
46) more /etc/system
this file has all n/w, h/w, memory etc tunable parameters/values

47) more /etc/inittab
after the bootup checks this file for which runlevel to enter

48) find / -name <file_name> -print
for finding any file name. ( giving '/' will find files from root directory)
49)hostname
will give your system name.
50)uname -a
will show system name, solaris version, platform and some more information
51)useradd
will add user (u have to root user to do this)
it has more options for specifying home directory, shell group etc.

Similarly userdel deletes username
52)df -k
will show all the mounted filesystems.
53)mount
will show all mounted file systems with additional info like large filesystem support etc

54)pkginfo
Gives/shows info about installed packages/software on system
55)showrev -p
shows all patches installed on system
56)init 0
will shutdown the system
57) init 6
will reboot the system (other init options are 1, 2, 3, 5 and S)
58)cd /var/adm
this directory has system/application logs. Please check all the files and its contents for more information.
59)cd /etc/rc.d
this directory has all startup scripts.
there will be more of this kind.
rc2.d, rc3.d, rc0.d, rc5.d, rc6.d etc...
each directory has scripts which will run in its own run level.
a run level is nothing but the init option u give while starting or stopping the system
suppose you give init 0, system will check in /etc/rc0.d for all the files to be executed.

60) /usr/sbin/ifconfig -a
will show the ip-address of the system.
lo0  : loopback interface
hme0 : hundred MBPS n/w interface
qfe0 : quad ehternet interface

61)ping <hostname>
will ping and test connectivity between your system and the hostname you give in the ping.
you can also give ping <ip-address>


62) rm -r <directory>
will delete all the contents in the directory specified recursively (BE CAREFUL WHILE GIVING THIS COMMAND)

63)alias l='ls -l'
alias dir='ls -l|grep "^d"'
alias p='pwd'
alias c='clear'

Short cuts for commonly used commands

64)tar -cvf allfile.tar /<directory_name>   copies all files under directory to allfile.tar
tar -xvf allfile.tar    /home retrieves tar files to /home directory
tar -tvf allfile.tar   reads contents of allfile.tar


65)find . -type f -print -exec grep -i <type_ur_text_here> {} \;
 this is recursive grep

66) rm - <-filename>
for deleting special files
Ex:-
# ls -l
total 16
-rw-r--r--   1 root     other         13 Dec 24 14:57 -k
# rm - -k
# ls -l
total 0
#

67) rm "<file name>"
delete file names with spaces in between

for checking sun related h/w conf.

68) top --- shows all process and memory, cpu etc utilisation

69) prtconf  -- shows h/w, cpu, memory conf


70) mount   -- will show the disks mounted and all partitions


71) cd /usr/platform/sun4u/sbin/prtdiag -v  --- shows additional configuration of memory, cpu speed etc..


72) sysdef -- shows system h/w, memory, and other internal configurable/tunable 

paramters
73) ifconfig unplumb hme0   --- will disable ehternet interface hme0


74) ifconfig plumb hme0    --- will enable hme0


for performance monitoring and diagnosing bottlenecks

75) iostat  -- disk utilisation, cpu, io wait etc (iostat -xcM gives extented statistics of disk activity, cpu etc)
76) vmstat  -- memory and virtual memory utilisation


77) sar      -- system archive report, gives total system report for cpu, memory, disk, etcc
78) netstat   --- shows network statistics, like how many connected on which services/ports
79) mpstat  -- shows multi cpu statistics like load on each cpu.


80) psrinfo   -- gives processor/s information (online/offline)


81) nfsstat --- nfs mounted filesystems statistics


82) prstat --- shows process related statistics (present from solaris 2.7 and above)

for disk configurations u need ---

83) format -- will show all the disks configuration and partitions

 

84) prtvtoc -- shows disk partition/geometry info

85) uadmin 2 0
stops system immediately within 5 seconds(BE CAREFUL-- has to be to root)


86) halt
halts processor and reboots machine (BECAREFUL -- has to be root)


87)adb
debugging tool (for reading/debugging corefiles)


88) mkfile 60m jithendra
creates a filename of size 60mb which can be used for adding to swap space

89) swap -a jithendra
attaches the 60mb file to swap space (Very useful when swap space is running out)



90)swap -l
lists the swap contents


91) sleep 5
waits for 5 seconds (useful in shell scripts)

92)cat <file_name> |awk '{print $1}'
Prints the first field of the filed ($1, $2... can be used to display more fields)

93) :1,$s/<old>/<new>/g

use the above for global replacement of text in ascii files using vi editor

94) :1,$s/^M//g

remove Ctrl M character in text files using vi editor

95) isainfo -v
shows supported platforms (32-bit, 64-bit)

96)strings <file_name>
shows printable strings in any type of file (binary, object, text etc)

97)truss -p <PID>
shows system calls and signals (useful when debugging process)

98) stty erase ^H
sets backspace for deleting typed character


99) echo $TERM
shows terminal type like vt100, vt220 etc.
($PATH, $ORACLE_HOME etc can be used with echo)


100) set -o vi
While your shell is set to KSH use this command to display history of commands you are typing
Press ESCAPE and k for showing previous commands


101)env
shows all the environmental variables set to your current session

1 comment:

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