Linux commands: alias

Sep 11, 2020

Learn how the Linux alias command creates a shortcut for another command, like alias ll for ls -al, and how to make your aliases permanent in .bashrc.

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It’s common to always run a program with a set of options you like using.

For example, take the ls command. By default it prints very little information:

Terminal showing ls command output with just words.txt filename displayed

while using the -al option it will print something more useful, including the file modification date, the size, the owner, and the permissions, also listing hidden files (files starting with a .:

Terminal showing ls -al output with detailed file permissions, owner, size and modification date for words.txt

You can create a new command, for example I like to call it ll, that is an alias to ls -al.

You do it in this way:

alias ll='ls -al'

Once you do, you can call ll just like it was a regular UNIX command:

Terminal showing alias creation with alias ll equals ls -al and then using ll command to display detailed file listing

Now calling alias without any option will list the aliases defined:

Terminal showing alias command output displaying the defined alias ll equals ls -al

The alias will work until the terminal session is closed.

To make it permanent, you need to add it to the shell configuration, which could be ~/.bashrc or ~/.profile or ~/.bash_profile if you use the Bash shell, depending on the use case.

Be careful with quotes if you have variables in the command: using double quotes the variable is resolved at definition time, using single quotes it’s resolved at invocation time. Those 2 are different:

alias lsthis="ls $PWD"
alias lscurrent='ls $PWD'

$PWD refers to the current folder the shell is into. If you now navigate away to a new folder, lscurrent lists the files in the new folder, lsthis still lists the files in the folder you were when you defined the alias.

The alias command works on Linux, macOS, WSL, and anywhere you have a UNIX environment

Tagged: CLI · All topics

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