Navigating the command line

One of the first jobs I got in IT was at a local webhost. That was exactly 20 years ago and at that time I was an avid Emacs user who had learned enough Perl¹ to use it to provide the business logic of my hobby websites as CGI scripts.

The ones who influenced me the most at that place were the devops guys². They were heavy vim users and smirked at my Emacs usage. They also influenced me to start using PHP in favor of Perl as that performed much better with the mod_php module that they had installed on the webservers.

Slowly but surely, my Perl scripts became PHP scripts and Emacs was soon replaced by vim (and later neovim). While PHP has since fallen out of fashion, vim is still my editor of choice - it’s perfect in the terminal and you can find it on every Unix-like system out there.

It’s interesting what you might get influenced by.

So why do I mention this?

Besides the quite inefficient “Windows” way of navigating text (using the arrow keys), learning both Emacs and vim means you know how to effectively input text using the most commonly used ways of doing so (at least to my knowledge).

I guess the most commonly used shells are bash (default on most Linux distros) and zsh (default on MacOS). Both of these shells default to Emacs-like keybindings³. Interestingly enough, both support vi keybindings as well, but I’ve never seen anyone using them. And to be honest, even for vim users, Emacs keybindings work so much better in the shell.

So if you want to effectively input text in the shell, don’t cheat by using the arrow keys. Take the time to learn basic Emacs keybindings. It will pay off in the long run.

There are a few keybindings that are essential to know:

Navigation with Ctrl:

• Ctrl-a - move to the beginning of the line
• Ctrl-e - move to the end of the line
• Ctrl-u - delete from the cursor to the beginning of the line
• Ctrl-k - delete from the cursor to the end of the line
• Ctrl-w - delete the word before the cursor
• Ctrl-d - delete character under cursor (or exit shell if line is empty)

Navigation with Alt (Meta):

• Alt-f - move forward one word
• Alt-b - move backward one word
• Alt-d - delete the word after the cursor
• Alt-Backspace - delete the word before the cursor

Extras with Ctrl:

• Ctrl-r - search backwards in history
• Ctrl-s - search forwards in history
• Ctrl-p - go to the previous command in history
• Ctrl-n - go to the next command in history
• Ctrl-y - paste the last deleted text
• Ctrl-l - clear the screen
• Ctrl-c - kill the current process
• Ctrl-z - suspend the current process (use fg to resume)
• Ctrl-Shift-c - copy the selected text
• Ctrl-Shift-v - paste the copied text

Extras with Alt:

• Alt-t - transpose characters before cursor with the character under cursor
• Alt-y - paste the last deleted text
• Alt-? - show the list of all possible completions
• Alt-* - insert all possible completions
• Alt-~ - expand the current word to all possible completions

If you need to type in a commond that spans multiple lines, I’m sure you know that you can use ’\’ and ‘Enter’ to continue on the next line, like so:

curl -X POST \
     -H "Content-Type: application/json" \
     -d '{"key": "value"}' \
     https://example.com

The problem with this approach, however, is that if you want to go back and edit something on a previous line, you’re stuck.

What will save the day is hitting Ctrl-x Ctrl-e which will open the command in your default editor (in my case, vim). Now it’s super-easy to edit the command in the comfort of your favorite editor, and when you’re done, just save and exit and the command will execute.

Oh, by the way. This is how you can enable vi keybindings.

In bash:

set -o vi

In zsh:

bindkey -v

But please just ignore this and learn the Emacs keybindings instead⁴.