1.Linux Shell Scripting-Intro.txt

$ man man
$ man command
  man -k passwd   // show all pages with keyword
  man –K passwd  // will search all manual pages for pattern
$ man passwd

********************************************************************************
-----------------------------------------------------
Section number		Subject area
-----------------------------------------------------
1			-User commands

2			-System calls

3			-Library calls

4			-Special files

5			-File formats

6			-Games

7			-Miscellaneous

8			-System admin

9			-Kernel routines


$ man 1 command
$ man 5 command
$ man 5 passwd
********************************************************************************

$ whatis passwd //get brief information about the command{

		Output:
		passwd (1ssl)        - compute password hashes
		passwd (1)           - change user password
		passwd (5)           - the password file


}


$ which passwd  //check the location of a binary file{

		Output:
		/usr/bin/passwd

}

$ whereis passwd //get complete information about the binary file location as well as manual page location{

		Output:
		passwd: /usr/bin/passwd /etc/passwd /usr/bin/X11/passwd /usr/share/man/man1/passwd.1.gz /usr/share/man/man1/passwd.1ssl.gz /usr/share/man/man5/passwd.5.gz


}

$ whoami //Change the user login

$ su //displays the user name of the logged in{

		/*******************************************************************************
		The su command (switch user) will make the user as the administrator; 
			but, you should know the administrators, password. 
		The sudo command (superuser do) will run the command with administrator's privileges. 
			It is necessary that the user should have been added in the sudoers list.
		*******************************************************************************/

}

# who am i //show the effective user who is working at that moment

# exit

$ alias ll='ls –l' //create new commands from existing commands
$ alias copy='cp –rf'