How to create and storing Alias in Linux

  • Aliases let you create shortcuts to commands
    • alias dir='ls -laF'
  • Use alias by itself to see all set aliases
  • Use alias followed by an alias name to see alias value
    $alias dir
    alias dir='ls -laF'

Alias

Aliases are shortcut names for longer commands. If you have commands that you run often, but take a considerable amount of typing, you can reduce these to an alias:
[user@statuionX ~]$ alias lf="ls -FCa"
The alias value must be a single word and so you will almost always want to quote the value as shown.
Even a relatively short command, if executed often, can save considerable typing if reduced to an alias:
[user@stationX ~]$ alias c=clear
Aliases can also be used for security purposes to force you to use certain flags:
[user@stationX ~]$ alias rm="rm -i"
In this case, if you ever want to use the rm command itself, instead of your alias, you can precede the command with a backslash:
[user@stationX ~]$ \rm -r Junk

Example: –

Goal

Create an alias that provides easy acccess to your shell’s history, and which is re-instated automatically for new shells.

  1. Device a command that would print the last 10 lines of bash’s command history.
    Suggested Solution:
    history 10
  2. Create an alias called h that runs the history command devised above:

    [amar@amar-pc ~]$ alias h='history 10'
    [amar@amar-pc ~]$ alias
    alias h='history 10'
    ..... output omitted ....
  3. Create a new shell (for example, by opening a new tab with Ctrl-Shift-t).
  4. Attempt to execute the h alias. This should not work. Why?
  5. Open ~/.bashrc in a text editor and locate the line:
    # User specific aliases and functions
    Add your alias to the line immediately below:
    alias h=’history 10′
    save the file and exit.

    Note: if not found ./bashrc file then you can create.
  6. Source the newly modified file:
    [amar@amar-pc ~]$ source ~/.bashrc
  7. Attempt to run h again. This time it should succeed. The same should be true if you create another new shell.

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