git-merge-ff

   1 #!/bin/bash
   2
   3 # stolen from http://stackoverflow.com/questions/4156957/merging-branches-without-checkout/4157435#4157435
   4
   5 _usage() {
   6     echo "Usage: git merge-ff <branch> <committish-to-merge>" 1>&2
   7     exit 1
   8 }
   9
  10 _merge_ff() {
  11     branch="$1"
  12     commit="$2"
  13
  14     branch_orig_hash="$(git show-ref -s --verify refs/heads/$branch 2> /dev/null)"
  15     if [ $? -ne 0 ]; then
  16         echo "Error: unknown branch $branch" 1>&2
  17         _usage
  18     fi
  19
  20     commit_orig_hash="$(git rev-parse --verify $commit 2> /dev/null)"
  21     if [ $? -ne 0 ]; then
  22         echo "Error: unknown revision $commit" 1>&2
  23         _usage
  24     fi
  25
  26     if [ "$(git symbolic-ref HEAD)" = "refs/heads/$branch" ]; then
  27         git merge $quiet --ff-only "$commit" --
  28     else
  29         if [ "$(git merge-base $branch_orig_hash $commit_orig_hash)" != "$branch_orig_hash" ]; then
  30             echo "Error: merging $commit into $branch would not be a fast-forward" 1>&2
  31             exit 1
  32         fi
  33         echo "Updating ${branch_orig_hash:0:7}..${commit_orig_hash:0:7}"
  34         if git update-ref -m "merge $commit: Fast forward" "refs/heads/$branch" "$commit_orig_hash" "$branch_orig_hash"; then
  35             if [ -z $quiet ]; then
  36                 echo "Fast forward"
  37                  git diff --stat "$branch@{1}" "$branch" --
  38             fi
  39         else
  40             echo "Error: fast forward using update-ref failed" 1>&2
  41         fi
  42     fi
  43 }
  44
  45 while getopts "q" opt; do
  46     case $opt in
  47         q ) quiet="-q";;
  48         * ) ;;
  49     esac
  50 done
  51 shift $((OPTIND-1))
  52
  53 case $# in
  54     2 ) _merge_ff "$1" "$2";;
  55     * ) _usage
  56 esac