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    Wednesday, September 05, 2012

    How to give an alias entry in Linux

    Alias entry in Linux is something where you assign a alias or supplementary name for a particular command. This can be done to save your time. You must be wondering how so let me explain my self with some examples below:

    I have used these commands in RHEL and CentOS so I am not aware of the same in other distributions of Linux.

    For example it happens that there is some command which I use very frequently like
    # netstat -ntlp
    So every time in the above command I need to add the switch along with the command so to save my time I can make an alias entry where the next time if I want to use the same command with the same switches I will use some shortcut command.

    From the terminal
    # alias netstat='netstat -ntlp'
    So once I type this command and hit enter, next time I only need to type netstat and I would get the output for "netstat -ntlp". It is not mandatory for you to use the same command name in the alias entry as it depends on the user. In the above case I could have given "deepak" as an alias entry for "netstat -ntlp" but it would be difficult to memorize the name for the command if there are multiple such entries.

    Now, to check all the system default alias entry in your machine
    # alias
    alias cp='cp -i'
    alias l.='ls -d .* --color=auto'
    alias ll='ls -l --color=auto'
    alias ls='ls --color=auto'
    alias mv='mv -i'
    alias rm='rm -i'
    alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

    NOTE: The method which I explained you above will be session dependent so the next time you change your session or terminal again you will have to make an entry for alias. To get rid of this hectic situation you can make your alias entry in .bash_profile located inside root
    # cd /root# vi .bash_profilealias
    netstat='netstat -ntlp'

    Now run the bash file
    # . .bash_profile
    Now every time you login to your machine the mentioned alias entry will be updated and can be used.

    To remove the alias entry of any command
    # unalias "alias name"
    # unalias netstat

    But again this command will be session dependent until and unless you make changes in .bash_profile.



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