Unix uses the ls command to list the contents of a directory. By default ls displays all directories and files the same way, leaving you without the ability to quickly determine what type of files you are looking at (in Unix everything is a file). Here is an screenshot showing the default output of ls on OS X:

Default OS X ls output

ls has the ability to color code different file types by passing the --color option to ls. For example, type the following command at your shell prompt to see colorized output:

ls --color

Here is what that command looks like:

OS X tweaked ls output

If you get an error statement after running the last command then you most likely do not have the GNU version of ls installed. You can download the GNU version of ls by downloading and installing the GNU Coreutils package for your OS.

If you are not using xterm as your terminal you may have to set the TERM environment variable to xterm or xterm-color. The TERM setting you choose will depend on your OS and distribution. You change your TERM variable by running the following:

export TERM=xterm-color


export TERM=xterm

To make your TERM environment variable persistent you add either of the commands above to your $HOME/.bash_profile or $HOME/.bashrc just like we did for the alias definition.

To customize the color ls displays you must modify the LS_COLORS environment variable. LS_COLORS is formatted as a string of variables separated by colons. Changing LS_COLORS is out of the scope of this howto. I have explained the LS_COLORS variable in detail here.

Creating an Alias

Typing ls --color everytime you need to use ls seems a little tedious, that is where the wonderful alias command comes in. alias allows you to create a shorthand definition to replace a command or a series of commands. To create an alias you can either put your alias definition in the $HOME/.bash_profile or $HOME/.bashrc which is persistent across multiple logins and shells or you can specify an alias definition at the command line. Examples of both are below:

Adding an alias definition to $HOME/.bash_profile

echo "alias ls='ls --color'" >> $HOME/.bash_profile

If you want to put the alias definition in $HOME/.bashrc just substitute it instead of $HOME/.bash_profile in the example above.

Create an alias definition that will only be valid for your current shell session perform the following:

alias ls='ls --color'

Now whenever you use ls it will use colored output.