The Story

I manage every one of my Chef cookbooks as a single git repository, complying with the BerkShelf paradigm. I keep them all as submodules in a "supermodule", to allow my teammates to easily clone them all. I can use git status from the supermodule to get submodule information when it comes to untracked/modified files, like so:

$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)
  (commit or discard the untracked or modified content in submodules)

    modified:   cookbooks/some-cookbook (untracked content)
    modified:   cookbooks/other-cookbook (modified content)

While this is nice, I wanted something more detailed, like git's PS1 prompt. I ended up using just that.

The script

I'm utilizing git submodule foreach, which cds into every sudmodule while populating some variables (e.g. $name is the submodule's name) and executes something (using some subshell).
I started checking how the prompt script calculates its symbols, but after reading the script I found it full of ifs and cases and lions and tigers and bears. I decided that the prompt script actually generates the string I need, so I should just execute it.
The only caveat is that the script reads variables defined in ~/.bashrc and are not exported, like this:

GIT_PS1_SHOWDIRTYSTATE='y'

Meaning that they're not available in any bash instances that aren't login instances. You can either:

  1. Edit ~/.bashrc to export the variables, like:

    export GIT_PS1_SHOWDIRTYSTATE='y'
    
  2. add this bit of trickery, which runs a bash login shell, extracts the variables and exports them:

    export $(bash -ic 'declare -p' | grep GIT | cut -f 3 -d ' ')
    

I chose option 2

The script looks like this:

#!/bin/bash
export $(bash -ic 'declare -p' | grep GIT | cut -f 3 -d ' ')
git submodule foreach --quiet 'bash -c ". /usr/lib/git-core/git-sh-prompt; __git_ps1";echo " $path"'

And the result looks like:

 (master %=) cookbooks/some-cookbook
 (master *=) cookbooks/other-cookbook
 (master=) cookbooks/untouched-cookbook
 (master>) cookbooks/notpushed-cookbook 

Very nice.