Persisting Aliases in Command Lines#

Using shell aliases in the command line can help streamline tasks repeated on a day-to-day basis. An alias replaces a command with an alternative, usually shorter, command. A catch is that aliases last until the current shell session ends. This vignette reminds me of how I can create and persist aliases for command-line interpreters—like the Git Bash terminal.

Statement of Need#

Using aliases in the command line can save time by using custom shorthands. For example, instead of typing out ls -al every time to view the contents of a directory in a long format, I can create an alias called ll that performs the same function. This can be especially useful for long or complex commands that are difficult to remember.

Example of Git Aliases#

An example of an alias is in the Git version control workflow. A common alias in Git is to add a last command which is the short form of git log -1 HEAD like this:

$ git config --global alias.last 'log -1 HEAD'
$ git last

commit 66938dae3329c7aebe598c2246a8e6af90d04646
Author: Josh Goebel <dreamer3@example.com>
Date:   Tue Aug 26 19:48:51 2008 +0800

    Test for current head

    Signed-off-by: Scott Chacon <schacon@example.com>

instead of doing

git log -1 HEAD

to get the same information. Aliases potentially save a lot of time for tasks that are done frequently.

Another example (outside of Git) is if I’m in a directory with a text file, like a setup.py, and I want to edit it. I can use the mouse to navigate that same path, double-click, and open the text file to edit it.

Aggravation #1: This can sometimes be one too many keystrokes and mouse clicks.

Solution: I can just do

$ notepad setup.py

(or whatever is the notepad-equivalent text editor shipped with the OS) right there in the directory from the command line.

But for another text editor like the Sublime Text editor, I need to define an alias for it to open setup.py.

Create an Alias#

I can create an alias for Sublime Text by doing

$ alias subl="/d/Program\ Files/Sublime\ Text\ 3/sublime_text.exe"

where subl is the new alias I (think I) want for the Sublime Text editor. "/d/Program\ Files/Sublime\ Text\ 3/sublime_text.exe" is the path of the Sublime Text executable file.

To confirm that the alias is registered, do a

$ alias
alias ll='ls -l'
alias node='winpty node.exe'
...
alias subl='/c/Program\ Files/Sublime\ Text/sublime_text.exe'

I can now edit setup.py using Sublime Text by doing

$ subl setup.py

Aggravation #2: Unfortunately, an alias lasts only the life of the shell session. Once I exit Git Bash, the alias is gone. The next time I open the command line again and do a subl I get the rude that message that:

$ subl setup.py
bash: subl: command not found

Persist the Alias (Pt. 1)#

Solution: Persist the new alias by adding it to the bashrc file. Open the bashrc file

$ notepad ~/.bashrc

and append alias subl="/d/Program\ Files/Sublime\ Text\ 3/sublime_text.exe" to the end of the file. Save and close. So the next time I open Git Bash my alias still works.

Aggravation #3: I later discovered that the above solution did not work on another machine that also uses Windows OS + Git Bash. So defining new aliases in bashrc did not work on my other machine.

An alternative is to do a source ~/.bashrc every time I start a Git Bash session so that the aliases are sourced from the bashrc file. But that is again too many keystrokes and an extra command to remember.

On further investigation, it turns out that Git Bash does not start the shell using the ~/.bashrc file. It uses the /etc/profile file as well as one of the three following files (if they exist) in order of precedence:

  • ~/.bash_profile

  • ~/.bash_login

  • ~/.profile

The ~/.bashrc file, and the aliases definitions within are thus ignored.

Persist the Alias (Pt. 2)#

Solution: The fix that finally ended up working for me is to open the ~/.bash_profile file using

$ notepad ~/.bash_profile

and appending source ~/.bashrc to the end of the file. Save and close. The aliases will now work every time I start a new terminal session by sourcing the aliases from ~/.bashrc on start-up.

Multiple Aliases for the Same Command#

Aggravation #4: Apparently, I forgot what alias I defined for Sublime Text more than once and ended up defining multiple aliases for the same command. Multiple aliases for the same command is ok.

Solution: For example, I can define multiple aliases for the same Sublime Text editor by adding

alias sblt="C:/Program\ Files/Sublime\ Text/sublime_text.exe"
alias subl="C:/Program\ Files/Sublime\ Text/sublime_text.exe"
alias sublime="C:/Program\ Files/Sublime\ Text/sublime_text.exe"

to the ~/.bashrc file.

Aliases of Aliases#

It’s also possible to define multiple aliases as

alias sblt="C:/Program\ Files/Sublime\ Text/sublime_text.exe"
alias subl=sblt
alias sublime=sblt

(It’s turtles all the way down.)

Resources#