How do I assign alias(es) to my Bourne Again Shell (bash)? 




  




	

	
    
	
  1. 
		Syntax for Defining Alias
	
  2. 
		Bourne Again shell (bash) alias examples
	
  3. 
		Managing Alias(es)
	












        Syntax for Defining Alias





  





Alias is a pseudonym  or shorthand for a command or series of commands, i.e., 
a convenient macro for frequently used command or a series of commands.
An alias definition affects the current shell execution
environment  and the execution environments of the subshells
of the current shell. The alias definition will 
not affect the parent process of the current shell  
nor any utility environment invoked by the shell.



For Bourne Again shell (bash), you can
define alias(es) using





alias  alias_name='command'





syntax in .bashrc file in your root
directory. You can define as many aliases as you want (as long as you
can remember alias names) in .bashrc.






        








        Bourne Again shell (bash) alias examples





  








        
	
                
        
        
	
	Collection of useful aliases







For example, to create a simple command alias, first open your .bashrc file in your home directory using any text
editor of your choice. 




alias del='rm -i'





This creates an alias del for the command 
"rm -i" which prompts you for confirmation that you want to remove a
file before it does so.



To create a command alias that consists of a series of commands,





alias llm='/usr/bin/ls -Flsa $1'





This creates an alias llm for the command 
"ls" with "Flsa" flags 
on a user-given directory name (=$1).



Of course, you can refer to another command alias within an alias,





alias h=history

alias rev='h | tail -10'





The first command assigns an alias h to the
"history" command. The next
command assigns another alias rev to the
command "h | tail -10". This
takes the output from the alias h (= the
"history" command) and pipes it through the "tail" command to list the ten most
recent commands in the command history.



Here's an example for using more than one alias on the same command line,





alias root='cd /; '

alias slist='ls -l | head -5'





Provided the last character in the root
alias definition is a blank space (" "). Thus any argument to this alias
as also checked to see if it is an alias. If so, it is executed. Also,
notice that in the first alias definition the command ends in a ";"
(semicolon) to allow another command to follow it.



If you type these two aliases, root slist at
the command prompt, then you're changing to your system root directory
and its contents is listed in a long format with only the first five
lines of output being displayed.






        







        Managing Alias(es)





  





    

  1. To display the value of an alias known to the shell,
type; 

    


    
$ alias

    

    

To display the current value for a particular alias, use
the command;

    


    
$ alias  name_of_alias

    

    

For example, to display the current value of the alias
named llm;

    


    
$ alias  llm
    
alias llm='/usr/bin/ls -Flsa $1'

    

    

    


  2. Once alias definition is save in .bashrc, the alias will be in effect next time you
login. If you wish to make the alias in effect immediately, update your
alias definition by sourcing out .bashrc.

    


    
$ . .bashrc

    

    

    


  3. To cancel a command alias during your current login
session use the command;

    


    
$ unalias  name_of_alias

    

    

For example,

    


    
$ unalias  llm

    

    

will cancel the command alias llm for your
current login session. You will have to remove the alias definition from
your .bashrc file if you want to cancel the
alias permanently.







For further details, RTFM on "alias."