Showing git branch in fish shell prompt. Put following code at the end of ~/.config/fish/config.fish. It will also highlight in red if branch is dirty. Based on http://zogovic.com/post/37906589287/showing-git-branch-in-fish-shell-prompt

config.fish

set fish_git_dirty_color red
set fish_git_not_dirty_color green

function parse_git_branch
  set -l branch (git branch 2> /dev/null | grep -e '\* ' | sed 's/^..\(.*\)/\1/')
  set -l git_status (git status -s)

  if test -n "$git_status"
    echo (set_color $fish_git_dirty_color)$branch(set_color normal)
  else
    echo (set_color $fish_git_not_dirty_color)$branch(set_color normal)
  end
end

function fish_prompt
  set -l git_dir (git rev-parse --git-dir 2> /dev/null)
  if test -n "$git_dir"
    printf '%s@%s %s%s%s:%s> ' (whoami) (hostname|cut -d . -f 1) (set_color $fish_color_cwd) (prompt_pwd) (set_color normal) (parse_git_branch)
  else
    printf '%s@%s %s%s%s> ' (whoami) (hostname|cut -d . -f 1) (set_color $fish_color_cwd) (prompt_pwd) (set_color normal)
  end
end

Initially I had mine working more or less like this, using git branch command to fetch branch name.
Then, when creating some new project (and thus, an empty git repo with it), git branch failed to show that I was on any branch and the prompt did not show up.

I've found parsing git status to be more reliable since it also works on repo's without any commits.
To fix this for empty repo's, replace set -l branch ... line with set -l branch (git status | head -1 | string split ' ')[-1].

Given this git status for a repository with commits:

On branch master
Your branch is up to date with 'origin/master'.

nothing to commit, working tree clean

And this one for a repository without commits:

On branch master

No commits yet

nothing to commit (create/copy files and use "git add" to track)

Both will correctly return the branch master.

Cheers for the git status -s switch, better than also parsing the last line of git status :) Too bad git branch fails to show a branch without commits present, too :(

Thanks for this

You can also just type fish_config on the command line, click on prompt and select a prompt with the current branch from the large number of prompts offered. I use lonetwin.