Linux Tips: Bind Keys

In most shells, it’s possible to bind a command to a key (or series of keys). This should not be confused with an alias, which lets us define a shortcut command. Let’s look at aliases first, then key bindings.

Aliases

We’ll use a git command to demonstrate aliases, but the same principle applies to any command. If you work with git much, you’re probably used to issuing the git status command to see which files have been modified in the repository you’re working in:

$ git status 
On branch master 
Your branch is up-to-date with 'origin/master'. 
Untracked files: 
 (use "git add <file>..." to include in what will be committed) 

       testrt.py 
       todo.txt 

nothing added to commit but untracked files present (use "git add" to track)

We can make that simpler by defining an alias:

$ alias gits="git status" 
$ gits 
On branch master 
Your branch is up-to-date with 'origin/master'. 
Untracked files:
[...]

Here, we alias gits to the git status command, and now typing gits followed by return has the same effect as typing the command in full.

Bind Keys

When we bind a key or keys to a command, simply typing those keys will run the command. There are lots of options, but we’ll keep it very simple here. Let’s bind Alt-Return to the git status command:

bind -x '"\e\r": git status'

Step by step:

• bind is a bash built-in command
• -x defines this as a shell command binding (as opposed to a function name or readline command)
• The single quote enclosing the rest of the command prevents command substitution within it
• "\e\r" is an escape sequence where \e is the escape key and \r is return. When Alt-Return is typed, the key sequence generated is Escape Return.
• The colon terminates the key sequence
• git status is the shell command to bind to the key sequence

Now, typing ESCAPE followed by return will run the git status command. You can also type Alt-Return, which will generate the same key sequence.

So now when you’re working with git, a simple Alt-Return will show the status of the repository.

Scratching the Surface

There’s a lot more that can be done with key bindings, and maybe we’ll revisit them in a future Linux Tips article.

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