Thursday, 7 August 2014

Linux Basic Commands

Basic Commands
1.ls -l for listing the files as well as directories those are kept in
the particular working directory
syntax
[root@nettech root]#ls -l
2.ls -la same as 'ls -l'but by this command we can also see the hiden
files.
syntax
[root@nettech root]#ls -la
3.ls -li same as 'ls -la' but it will also shows us the inode number of
each and every file
syntax
[root@nettech root]#ls -li
4.ls by this command we can see only file name nothing else
syntax
[root@nettech root]#ls
5.clear it will clear the screen(short cut ctl+l)
syntax
[root@nettech root]#clear
6.exit to end a current session as well current terminal logging
syntax
[root@nettech root]exit
7.touch to create a new empty file
syntax
[root@nettech root]#touch
8.cd to change the working/present directory
syntax
[root@nettech root]#cd /home/mango
where '/home/mango' is the desired directory to be change from
'/root'
9.cat to view the contents of a file and it is also used for creating a
new file with some contents
syntax
[root@nettech root]#cat <file name> to view file contents
[root@nettech root]#cat > newfilename enter,then you can write something in
the file and then to save the file contents press clt+d then enter
10.mkdir to make a new directory
syntax
[root@nettech root]#mkdir newdirname
you can also create a directory at your desired path without
changing your present working directory
syntax
[root@nettech root]#mkdir /home/mango/newdirname
11.rm to remove a empty file
syntax
[root@nettech root]#rm filename
Basic Commands
12.rmdir to remove a empty directory
syntax
[root@nettech root]#rmdir directoryname
13.rm [-i/-r/-f] to remove a directory with its subdirectories as well as its
files that is to remove a directory which already contains some files in it
syntax
[root@nettech root]#rm -i directory/filename
-i stands for interactively
-r stands for recursively
-f stands for forcefully
14.cp to copy something in a destination file or directory
syntax
[root@nettech root]#cp sourcepath destinationpath
example: [root@nettech root]#cp /home/mango/webmin.rpm /root/abcd
in this example the webmin.rpm file will be copied in
/root/abcd directory
15.mv to move one file or directory from one place to another place, it
is also used for renaming adirectory or file
syntax
[root@nettech root]#mv source destination
[root@nettech root]#mv oldfilename newfilename [to change the file name]
16.man to view the mannual page of commands for syntax
syntax
[root@nettech root]#man commandname
17.info to view the information about any command
syntax
[root@nettech root]#mkdir info
18.--help to view the help doccuments of a command
syntax
[root@nettech root]#commandname --help
19.dir to view the subdirectories and filesn under the directory
syntax
[root@nettech root]#dir
20.su - to become a super user
syntax
[mango@nettech mango]$su -
output wil be
[root@nettech root#]
21.who by this command you can see the user name and their ip addresses
who have loged in on your server
syntax
[root@nettech root]#who
22.whoami this command shows your current logged in terminal user name
syntax
[root@nettech root]#whoami
23.who am i this command shows you the logged in terminal number and user
name and more detailed information
Basic Commands
syntax
[root@nettech root]#who am i
24.pwd to view the present working directory
syntax
[root@nettech root]#pwd
25.rpm -ivh to intall a rpm package
syntax
[root@nettech root]#rpm -ivh packagename.rpm
rpm stands for 'redhat package manager'
-i stands for install
-v stands for verbose mode
-h stands for with hash sign(#)
26.rpm -q to querry about any rpm package
syntax
[root@nettech root]#rpm -q packagename
27.rpm -e to uninstall a rpm package
synatx
[root@nettech root]#rpm -e package
28.find / -name to find any file or directory in linux file system
syntax
[root@nettech root]#find / -name filename
29.su username to switch from one user to another users home directory
syntax
[root@nettech root]#su mango
output will be
[mango@nettech root]#cd
[mango@nettech mango]#
30.su - username to switch from one user to another user users home
directory directly
syntax
[root@nettech root]#su - mango
31.useradd to create a new user
synatx
[root@nettech root]#useradd username
32.passwd to give a password of a user
syntax
[root@nettech root]#passwd tarun
output will be
give a password for user tarun:(here you have to type a password for tarun user)
confirm password:(again type the same password)
33.userdel to remove a user from linux
syntax
[root@nettech root]#userdel tarun
Basic Commands
34.groupadd to add a new group
syntax
[root@nettech root]#groupadd groupname
35.gruopdel to delete a group
syntax
[root@nettech root]#groupdel groupname
36.chown to change the ownership of a file or directory
syntax
[root@nettech root]#chown ownername filename
example:
[root@nettech /]#ls -l
output
drwxrw-rw- 2 root root 4096 Mar 11 12:03 abcd
(permission) (own) (group own)(size) (name)
[root@nettech root]#chown tarun /abcd
in this example /abcd directory owner will be change to tarun user
effect
[root@nettech /]#ls -l
drwxrw-rw- 2 tarun root 4096 Mar 11 12:03 abcd
37.chgrp to change the group ownership of a file or directory
syntax
[root@nettec root]#chgrp newgroupownername filename
example
[root@nettech /]#ls -l
drwxrw-rw- 2 tarun root 4096 Mar 11 12:03 abcd
[root@nettech root]#chgrp tarun /abcd
effect
[root@nettech /]#ls -l
drwxrw-rw- 2 tarun tarun 4096 Mar 11 12:03 abcd
38.chmod to change the permission of a file or directory
drwxrw-rw- 2 root root 4096 Mar 11 12:03 abcd
(permission) (ownr) (grpownr) (size) (name) IN
OCTAL VALUE
d stands for directiry READ=4
r stands for read only permission WRITE=2
w stands for write only permission EXECUTE=1
x stands for execute only permission
drwxrw-rw- FIRST OCTET FOR DENOTING THE DIRECTORY OR FILE OR LINK FILE ETC.
SECOND THREE OCTET FOR USER OR OWNER PERMISSION (rwx OR 7 IN
OCTAL VALUE)
THIRD THREE OCTET FOR GROUP PERMISSION (rw- OR 6 IN OCTAL VALUE)
FORTH THREE OCTET FOR OTHERS PERMISSION (rw- OR 6 IN OCTAL VALUE)
SYNTAX
[root@nettec root]#chmod value fileordirectoryname
example
[root@nettech /]#ls -l
drwxrw-rw- 2 tarun root 4096 Mar 11 12:03 abcd
[root@nettech /]#chmod 402 /abcd
[root@nettech /]#ls -l
drw-----w- 2 tarun tarun 4096 Mar 11 12:03 abcd
40.usermod to modify the user profile

Basic Commands
synatx
[root@nettech root]#usermod -parameter groupname username

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