This my first venture into bash scripting, so I decided to make a port of posh-git, which, in my humble opinion, is fantastic (and can be found at found at https://github.com/dahlbyk/posh-git).

I based my work off of https://github.com/git/git/blob/master/contrib/completion/git-prompt.sh

This is distributed under the GNU GPL v2.0. I hope that you may find some use of it. Please do not hesitate to contact me about any issues or requests.

1. Copy this file to somewhere (e.g. ~/git-prompt.sh).

2. Add the following line to your .bashrc:

    source ~/git-prompt.sh
   

3. a. If you are using bash, __git_ps1 can be used for PROMPT_COMMAND with two parameters, <pre> and <post>, which are strings you would put in $PS1 before and after the status string generated by the git-prompt machinery. For example, the following

   PROMPT_COMMAND='__git_ps1 "\u@\h:\w" "\\\$ "'
   

   will show username, at-sign, host, colon, cwd, then various status strings, followed by dollar and space, as your prompt. Optionally, you can supply a third argument with a printf format string to fine-tune the output of the branch status.

By default, the status summary has the following format:

[{HEAD-name} +A ~B -C !D | +E ~F -G !H]

• {HEAD-name} is the current branch, or the SHA of a detached HEAD
• Cyan means the branch matches its remote
• Green means the branch is ahead of its remote (green light to push)
• Red means the branch is behind its remote
• Yellow means the branch is both ahead of and behind its remote
• ABCD represent the index; EFGH represent the working directory
• + = Added files
• ~ = Modified files
• - = Removed files
• ! = Conflicted files
• As in git status, index status is dark green and working directory status is dark red

For example, a status of [master +0 ~2 -1 | +1 ~1 -0] corresponds to the following git status:

# On branch master
#
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#        modified:   this-changed.txt
#        modified:   this-too.txt
#        deleted:    gone.ps1
#
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#
#        modified:   not-staged.ps1
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#        new.file

This should work out of the box, but there are some options available, mostly setting things in the local git config for per-repository options.

bash.enableFileStatus
bash.enableGitStatus
bash.showStatusWhenZero
bash.showUpstream

* true      Default. The script will query for all file indicators every
            time.

* false     No file indicators will be displayed. The script will not query
            upstream for differences. Branch color- coding information is
            still displayed.

* true      Default. Color coding and indicators will be shown.

* false     The script will not run.

* true      Default. An indicator will display if the stash is not empty.

* false     An indicator will not display the stash status.

* false     Default. No file change indicators will be shown if there are no
            changes to the index or working tree.

* true      Indicators will be shown even if there are no updates to the
            index or working tree.

By default, __git_ps1 will compare HEAD to your SVN upstream if it can find one, or @{upstream} otherwise.

* legacy    don't use the '--count' option available in recent versions of
            `git-rev-list`
            
* git       always compare `HEAD` to `@{upstream}`

* svn       always compare `HEAD` to your `SVN` upstream