Information-richness in a compact zsh Prompt

Note: While this post focuses on zsh, everything I do should be possible to implement in bash too.

When I look at people’s shell prompts, the first thing I always seem to notice is that they’re bulky and eye-grabbing. Seeing a textual version of GNOME Panel get duplicated into my terminal after every command isn’t something that appeals to me, so I thought I’d come up with something just as useful, but a little more compact.

What follows is a step-by-step story, with pseudo-screenshots, of how I went from a bog-standard zsh prompt to a fairly advanced prompt that only looks different when it has something to say, ending in a link to the .zshrc source I use to actually implement it. Feel free to skip ahead.

Because I like the color scheme and because I already have it, I’m starting with the default Gentoo prompt:

ssokolow@monolith ~ %

Obviously, this already has the usual Gentoo prompt’s “you are root” indicators (user ID turns red and % turns into #) and the ability to tell zsh and bash apart at a glance (For those who don’t know, zsh uses % while bash uses $) but I do a lot of programming and I use git for all my code, so the most useful thing I could possibly add is a way to never forget which branch I’m working on. Thankfully, that’s already been done for me:

ssokolow@monolith quicktile [master] %

I’d also wanted a way to see, at a glance, whether there were any jobs running in the background. The %(1j.%%.) ternary expression fixed that one right up:

ssokolow@monolith quicktile [master] % git gui &
ssokolow@monolith quicktile [master] %%

Finally, not all of my programs are clear about when they send a non-zero exit code, so it’d be nice to know that too. Another ternary expression, namely %(0?..%F{yellow}), takes care of that:

ssokolow@monolith quicktile [master] % false
ssokolow@monolith quicktile [master] %

I like how the prompt, by default, only displays the last component of $PWD so I left that unchanged. You’re free to add in other things but I tend to struggle with performance issues when both Firefox and GCC have to fight for “only” 4GiB of RAM so I decided not to hook in any more subprocess calls.

A pruned-down, streamlined version of the code for it is available on GitHub as zshrc.d/gentoo_prompt_setup but you’ll also need this line from my master .zshrc:

typeset -ga precmd_functions

Information-richness in a compact zsh Prompt by Stephan Sokolow is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.