Keystrokes are valuable especially if you live in the command line, and thankfully Bash (Terminal’s default command-line interpreter) allows you to create shortcuts using aliases.

Creating Aliases

Aliases are nothing more than keyboard shortcuts or abbreviations, and although they’re a bit limited, they’re great for simple commands.

Let’s create a temporary alias in the command line for ls -al (list all files in long listing format in the current directory). Open Terminal and run the following command:

alias ll="ls -al"

Note: There should be no spaces before or after the equal sign. Spaces will break the command.

Now if you type ll in the command line, you should see something like the following:

-rw-------    1 user  staff   6927 Feb 12 12:51 .bash_history
-rw-r--r--    1 user  staff   2787 Jan  3 20:16 .bash_profile
-rw-r--r--    1 user  staff     58 Apr  8  2014 .bashrc
drwxr-xr-x    5 user  staff    170 Jul 21  2014 .composer
drwxr-xr-x    5 user  staff    170 Dec  4  2013 .config
drwxr-xr-x    3 user  staff    102 Nov  4  2013 .gem
-rw-r--r--    1 user  staff    811 Feb  2 15:31 .gitconfig
drwxr-xr-x    5 user  staff    170 Apr  8  2014 .go
drwxr-xr-x  687 user  staff  23358 Feb  3 19:37 .npm

To remove the alias, use the unalias command:

unalias ll

To see a list of all your aliases, use the alias command:


Permanent Aliases

The problem with setting an alias in the command line is that it’s not permanent—if you open a new window or restart Terminal, the alias is gone.

To make aliases permanent, we have to set them in a file that’s read when you open Terminal. Some common ones are ~/.bashrc and ~/.bash_profile. For this example, let’s use ~/.bash_profile.

From the command line, open to edit the file by running the following:

nano ~/.bash_profile

(You can also open and edit it with your code editor, i.e. subl ~/.bash_profile)

Add the following lines either at the bottom of the file or wherever you’d like:

# -------
# Aliases
# -------
alias ll="ls -al"

Save and close the file. Now if you restart Terminal, the alias ll will be available to you. You can also tell Terminal to reload the ~/.bash_profile file using the source command:

source ~/.bash_profile

Useful Aliases

Here are a handful of aliases that you may find useful.

# -------
# Aliases
# -------
alias clr="clear" # Clear your terminal screen
alias flush="sudo discoveryutil udnsflushcaches" # Flush DNS (Yosemite)
alias flush="killall -HUP mDNSResponder" # Flush DNS (Mavericks, Mountain Lion, Lion)
alias flush="dscacheutil -flushcache" # Flush DNS (Snow Leopard, Leopard)
alias ip="curl" # Your public IP address
alias ll="ls -al" # List all files in current directory in long list format
alias ldir="ls -al | grep ^d" # List all directories in current directory in long list format
alias o="open ." # Open the current directory in Finder
alias ut="uptime" # Computer uptime

If you use Git in the command-line, I also wrote a post on Git Command-Line Shortcuts, which includes my personal set of Git Bash aliases and functions.