Understanding Basic Linux Commands

Mode of Login 

There are two mode of login

1. Text Mode  (Alt+ctrl+F1)
2. Graphical Mode (Alt+Ctrl+F7)

In case of Text Mode

Station2 Login : root

Password : redhat

[root@station2~]#

to switch from one text mode to another

Alt+Ctrl+F1 to Alt+Ctrl+F6

In case of Graphical Mode

Ctrl+Alt+F7

Common Commands

Some of the Common system command are as follow:

1. Date : to display date and time

2. Cal : to display the calendar

3. Cal 11 2006 : display the calendar of Month 11 and year 2006

4. Clear : To clear the screen

5. ls : to list directory contents

color identification

blue : Directories

White : Files

Green : Executable files

Red : Zip files, rpm, tar file

Different switches used with “ls” command

ls –l or ll : used for long listing including file and directory permission

            (-) : file

            (d) : Directory

            (l) : Symbolic link

ls –a  : shows all hidden files and directory. Any file followed by (.) is hidden file

ls –al : show all hidden files and directory with long listing or whole description

ls –d : shows all the directory

6. pwd: Print  working directory

7. who am I : display the information of current terminal  

8. who : display all the terminal in a network

9. history : it shows all the command your have used.

By default history stores last 1000 command which u have run. If u want to change

# vi /etc/profile

HIST SIZE =10

Save and exit

# history –c ( to clear all the previous command reside in history)

Creating file and Directory:

1. Creating file:

The ‘cat’ command is used to create a file

Syntax:

# cat > filename

example:

# cat > abc.txt

(Ctrl +D) is used to save the file.

2. View the content of file

Syntax:

# cat  filename

Example:

#cat abc.txt

#cat –b abc.txt

3. Creating Directory

The ‘mkdir’ command is used to create directory

Syntax:

Mkdir [directory_name]

Example:

# mkdir jeet

Option used:

cd : To change directory

cd .. : To come out from directory

cd : to jump to root directory

cd - : to jump to previous directory

Deleting Files and directory:

Syntax:

For file:

rm <filename>

example:

rm abc.txt

for directory

syntax:

rmdir <directory_name>

Note: Only empty directory will be deleted)

If we want to delete the tree structure of directory then we need to use the following command

Syntax:

rm –rf  <directory_name>

where

r = recursively

f= force

In order to remove non empty directory

Syntax:

rm –r <directory>

example;

rm –r jeet

this will remove directory step by step ,first remove  sub directory and then finally main directory.

Another method of creating file :

Touch : this command is used to create a blank file with size zero.

# touch <filename>

Example:

#touch abc

Copying File and Directory:

1. Copy file:

Syntax:

# cp [source]filename [destination]

2. Copy directory

#cp –r [source]directory [destination]

to copy a directory into another directory recursively

3. cp –rf [source]directory [destination]

to copy a directory forcely

syntax used for copy file or directory:

cp [option] file destination

option:

-I : interactive : ask before overwriting file

-r : Recursive

-p : Preserve

-f : forcely

More than one file can be copied at a time if the destination is directory

Syntax:

cp [option] file1 file2 file 3 Destination

Moving and Renaming File and Directory:

Syntax:

# mv : move /rename files and directory

Example:

# mv [option] file destination

example:

# mv t.txt /home/jeet/

more than one file can be moved at a time if the destination is a directory

# mv [option] file1 file2 file3 destination

Thanks ,