Promote an "upstream" Git branch by merging it into a "downstream" branch.

git-promote

#!/bin/bash -eu

git_promote="$(basename "$0" | sed -e 's/-/ /')"
HELP="Usage: $git_promote [options...] [upstream] <downstream>

Promote an \"upstream\" Git branch by merging it into a \"downstream\" branch.

When omitted, the currently checked out branch is used as upstream.

Options:
  -m <message>          # merge commit message, asked otherwise
  --dry-run             # echo git commands, do not execute them
  --nopull              # do not pull from remote
  --nopush              # do not push from remote
  --local               # same as --nopull and --nopush
  --help                # prints this

Examples:
  $git_promote qa       # promotes current branch to \"qa\"
  $git_promote qa prod  # promotes \"qa\" branch to \"prod\"
"
# to install copy to /usr/local/bin and
# sudo chmod +x /usr/local/bin/git-promote
# to install man page so that git(no dash)promote --help works:
# mkdir -p /usr/local/man/man1
# git-promote --help | txt2man -t git-promote | gzip | sudo tee /usr/local/man/man1/git-promote.1.gz >/dev/null

git='git'
commit_opts=''
pull_upstream='y'
pull_downstream='y'
push='y'

OPTS=$(getopt -o "m:" \
  -l dry-run \
  -l local \
  -l nopull \
  -l nopush \
  -l help \
  -- "$@") || (echo "$HELP" >&2 ; exit 1)

eval set -- "$OPTS"

while [ $1 != "--" ]; do
  case "$1" in
    -m)
      shift
      commit_opts="-m \"$1\""
      ;;
    --dry-run)
      git="echo git"
      ;;
    --nopull)
      pull_upstream='n'
      pull_downstream='n'
      ;;
    --nopush)
      push='n'
      ;;
    --local)
      pull_upstream='n'
      pull_downstream='n'
      push='n'
      ;;
    --help)
      echo "$HELP"
      exit 0
      ;;
  esac
  shift
done
shift # eat "--"

current="$(git branch | awk '/^[*]/{print $2;}')"

case "$#" in
  1)
    upstream="$current"
    downstream="$1"
    ;;
  2)
    upstream="$1"
    downstream="$2"
    ;;
  *)
    echo "$HELP" >&2
    exit 1
    ;;
esac

if [ -z "$current" ]; then
  exit 1
fi

function fail {
  $git checkout "$current" 2>/dev/null || true
  exit 1
}

trap 'fail' ERR INT TERM

if [ "$upstream" != "$current" ]; then
  $git checkout "$upstream"
else
  echo "Promoting $upstream to $downstream"
fi

if [ "$pull_upstream" == 'y' ]; then
  $git pull --ff-only
fi

$git checkout "$downstream"

if [ "$pull_downstream" == 'y' ]; then
  $git pull --ff-only
fi

$git merge "$upstream" --no-ff $commit_opts

if [ "$push" == 'y' ]; then
  $git push
fi

$git checkout "$current"

exit 0

# vim: set expandtab ts=2 sw=2

git-promote-completion.bash

#!bash

# bash completion for git-promote.
# install as /etc/bash_completion.d/git-promote-completion.bash

__git_promote_list_branches() {
    local nomerged=''
    if [[ ! -z "$1" ]]; then
        nomerged="--no-merged $1"
    fi
    git branch --list -r --no-color $nomerged 2> /dev/null \
        | sed 's/^ *//g' \
        | grep "^$origin/" \
        | grep -v 'HEAD' \
        | sed "s,^$origin/,," \
        | sort
}

__git_promote_parse_args_opts() {
    while [[ $# > 0 ]] ; do
        if [[ "$1" = -* ]]; then
            opts=("${opts[@]}" "$1")
            if [[ "$1" == '-m' ]]; then
                shift
            fi
        else
            args=("${args[@]}" "$1")
        fi
        shift
    done
}

_git_promote() {
    local OPTS=(
        '--dry-run'
        '--help'
        '--local'
        '-m'
        '--nopull'
        '--nopush'
    )
    local cur="${COMP_WORDS[$COMP_CWORD]}"

    local args=()
    local opts=()
    __git_promote_parse_args_opts "${COMP_WORDS[@]:2:$COMP_CWORD-2}"

    if [[ "$cur" = -* ]]; then
        local avail_opts=$(comm -23 \
            <(printf '%s\n' "${OPTS[@]}") \
            <(printf '%s\n' "${opts[@]}" | sort -u))
        __gitcomp "$avail_opts"

    elif [[ ${#args[@]} -lt 2 ]]; then
        local origin='origin'

        local from=''
        if [[ ${#args[@]} -gt 0 ]]; then
            from="$origin/${args[0]}"
        fi
        __gitcomp "$(__git_promote_list_branches "$from")"

    else
        COMPREPLY=()
    fi
}

Very handy when keeping multiple branches in parallel.

It doesn't work on all systems as BSD implementation of 'getopt' does not support parsing long options, therefore it might fail on FreeBSD, OS X, OpenBSD.

How about replacing long options with short ones or replacing 'getopt' with 'getopts' which is consistent across all environments?