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The command that are used to get the help are discussed as :

1. Whatis

Display a short description of command , it uses a database that is updated nightly. Often not available immediately after installation.

Syntax:

# Whatis cal

2. Help

Display usage summary and argument list

Syntax:

--help

Example:

#Date –help

3. Man and Info:

Both provide documentation for command. Almost every command has a “man” page. Collection of pages are called linux manual.

# man date

# info date

Viewing Text Page

Syntax:

#less [option] [filename]

Example:

# less abc.txt

scroll with arrows/PgUp /PgDown

/text : search for text

n : Next Match

Option:

-c : Clear before displaying

-s : Squeeze multiple blank lines into a single blank line

Simply we can also use “less” along with pipe | as

# ll |less

Moving and Renaming File and Directory

Syntax:

# mv : move /rename files and directory

Example:

# mv [option] file destination

example:

# mv t.txt /home/rohan/

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

# mv [option] file1 file2 file3 destination

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 forcefully

syntax used for copy file or directory:

cp [option] file destination

option:

-I : interactive : ask before overwriting file

-r : Recursive

-p : Preserve

-f : forcefully

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

Syntax:

cp [option] file1 file2 file 3 Destination

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 rohan

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

example:

rm abc.txt

for directory

syntax:

rmdir

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

where

r = recursively

f= force

in order to remove non empty directory

Syntax:

rm –r

example;

rm –r rohan

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

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

# touch

Example:

#touch abc

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)

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

Unix is the first Operating system in the world, developed by Kem Thompson and Dennis Ritchie in 1969 at Bell Lab by AT&T Company

IBM : AIX

SGI : IRIX

HP : HP

Sun : Solaris

FSF:

Free software foundation organization, they start a project by name GNU. The mail aim of this project is to develop such a O.S that can run on any platform.

In 1991, a student Linus Torvalds developed a kernel named Linus’s Kernel plus GNU application called Linux O.S

Linux is a open source technology.

Different companies that provide Linux in Market are Redhat, SuSe, Mandrake, Turbo, Knoppix etc.

Features:

1. Linux is the fastest Operating system in the world. It runs 2 to 3 times fast than windows O.S
2. Linux is the very secured O.S because there is no any problem of virus.
3. Linux file format is text format and windows file format is binary format.
4. Linux is very reliable O.S because kernel of linux is very stable as compare to windows kernel not crashed easily.
5. Kernel of linux is very small, it can be stored in floppy
6. Linux uses the x-Window system which is advanced network windowing system. Using this system we can display output of any workstation monitor attached in the network

1. Virus Proof
2. Crash Proof
3. Economical
4. Multiuser, multi desktop and multi tasking