18. alias

Typing long or repetitive commands can be tedious. Fortunately, you can create a shortcut, or a Linux alias, to make your command-line experience more efficient. The alias command lets you define a custom name for any command or sequence of commands.

Creating a Temporary Alias

To create a temporary alias that lasts for your current terminal session, you simply specify a name and set it equal to the command string.

For example, to create an alias named ll for the ls -la command, you would use the alias command linux syntax like this:

alias ll='ls -la'

Now, instead of typing ls -la, you can just type ll, and it will execute the same command. This is a simple yet powerful way to customize your shell.

Making an Alias Permanent

A temporary alias will disappear once you close your terminal or reboot your system. To make a command alias in linux permanent, you need to add it to your shell's configuration file. For the Bash shell, this file is typically ~/.bashrc.

1. Open the file in a text editor: nano ~/.bashrc
2. Add your alias definition to the file, just as you typed it on the command line:

alias ll='ls -la'
alias update='sudo apt update && sudo apt upgrade'

3. Save the file and exit the editor.

For the changes to take effect, you must either close and reopen your terminal or tell the shell to reload the configuration file using the source command:

source ~/.bashrc

Your Linux command alias will now be available every time you start a new terminal session.

Removing an Alias

If you no longer need an alias, you can remove it with the unalias command. This will remove it from your current session.

unalias ll

To remove a permanent alias, you must also delete its definition from your ~/.bashrc file.