Presented By Mr.Thanigairaj

1.
BASIC COMMANDS IN LINUX
Session – I
Kanchi Linux User Group
Presented By
­ Mr.Thanigai

2. Whoami :
arul@arul­desktop:~$ whoami
arul
This command helps to identify login user name
su :
arul@arul­desktop:~$ su ­
Password:
root@arul­desktop:~#
This command helps to Switch User from any user to Root user
Root user means (#) symbol will display at the end of terminal default
line.
Normal user ($) symbol will display . . .
logout :
root@arul­desktop:~# logout
arul@arul­desktop:~$
logout helps to logout from last login user
root@arul­desktop:~# su ­ arul
arul@arul­desktop:~$
su ­ ' user name ' will also helps to change the user
clear :
arul@arul­desktop:~$ clear
It helps to clear the terminal page (ctl + l )

3. ls :
arul@arul­desktop:~$ ls
Arulalan.jpg
arul_gsoc_2009
arul.pdf
Desktop
Documents
Examples
It helps to list out all files and directories
ls ­l :
arul@arul­desktop:~$ ls ­l
total 2068980
­rw­r­­r­­ 1 arul arul 29055 2009­05­23 23:38 Arulalan.jpg
drwxrwxrwx 3 amma shrini 4096 2009­04­05 14:53 arul_gsoc_2009
­rw­r­­r­­ 1 arul arul 34217 2009­05­29 19:16 arul.pdf
drwxrwxrwx 12 root root 4096 2009­05­31 14:46 Desktop
drwxrwxrwx 3 root root 4096 2009­05­17 15:39 Documents
It will display list of files with User , Group, Others Permissions and their size in
bytes.
ls ­lh :
arul@arul­desktop:~$ ls ­lh
total 2.0G
­rw­r­­r­­ 1 arul arul 29K 2009­05­23 23:38 Arulalan.jpg
drwxrwxrwx 3 amma shrini 4.0K 2009­04­05 14:53 arul_gsoc_2009
­rw­r­­r­­ 1 arul arul 34K 2009­05­29 19:16 arul.pdf
drwxrwxrwx 12 root root 4.0K 2009­05­31 14:46 Desktop
drwxrwxrwx 3 root root 4.0K 2009­05­17 15:39 Documents
It will display file size with human readable form .

4. pwd :
arul@arul­desktop:~$ pwd
/home/arul
It is precent working directory
cd cd .. cd ~
arul@arul­desktop:~$ cd Desktop/
arul@arul­desktop:~/Desktop$ cd ..
arul@arul­desktop:~$
cd : change directory
arul@arul­desktop:~/Desktop/Himalayas/linux $ cd ~
arul@arul­desktop:~$
cd ~ : ~ symbol helps to change directory from any where to home
directory.
arul@arul­desktop:~$ cd /home
arul@arul­desktop:/home$ ls
amma arul ftp lost+found shrini
sudo :
“ sudo “ helps to give root authendication permission for upcomming
commands followed by sudo, with current user's password.
adduser :
arul@arul­desktop:~$ sudo adduser
[sudo] password for arul:

5. adduser: Only one or two names allowed.
arul@arul­desktop:~$ sudo adduser god
Adding user `god' ...
Adding new group `god' (1004) ...
Adding new user `god' (1003) with group `god' ...
Creating home directory `/home/god' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for god
Enter the new value, or press ENTER for the default
Full Name []: GOD
Room Number []: 0
Work Phone []:
Home Phone []:
Other []:
Is the information correct? [Y/n] y
arul@arul­desktop:~$ cd /home
arul@arul­desktop:/home$ ls
amma arul ftp god lost+found shrini
adduser helps to add user
chmod :
arul@arul­desktop:~/klug$ ls ­l
total 564
drwx­­­­­­ 2 arul arul 4096 2009­05­26 23:50 bajji
­rwx­­­­­­ 1 arul arul 616 2009­05­18 11:08 kanchilug emails & b' days
­rw­r­­r­­ 1 arul arul 338 2009­05­22 19:43 kanchilug freelist
. . .
arul@arul­desktop:~/klug$ chmod o+rwx kanchilug emails & b' days
arul@arul­desktop:~/klug$ ls ­l
total 564
drwx­­­­­­ 2 arul arul 4096 2009­05­26 23:50 bajji
­rwx­­­rwx 1 arul arul 616 2009­05­18 11:08 kanchilug emails & b' days
­rw­r­­r­­ 1 arul arul 338 2009­05­22 19:43 kanchilug freelist

6. arul@arul­desktop:~/klug$ chmod 777 kanchilug freelist
arul@arul­desktop:~/klug$ ls ­l
total 564
drwx­­­­­­ 2 arul arul 4096 2009­05­26 23:50 bajji
­rwx­­­rwx 1 arul arul 616 2009­05­18 11:08 kanchilug emails & b' days
­rwxrwxrwx 1 arul arul 338 2009­05­22 19:43 kanchilug freelist
chmod : change mode : changing file(s) permissions ( read, write, excute ) to users
, groups , Others .
History :
arul@arul­desktop:~/klug$ history
1 <?xml version=quot;1.0quot;?>
2 <stickynotes version=quot;2.26.1quot;/>
.
.
.
173 chmod o+rwx kanchilug emails & b' days
174 ls ­l
175 chmod 777 kanchilug freelist
176 ls ­l
177 history
history helps to retrive past 500 commands excuted in terminal
eventhough after shutdown many times. ( By default 500).
we can change change the no of commands which will be store in
history file .
arul@arul­desktop:~/klug$ history > klug_history
we can store all those commands history into a text file .