--- /dev/null
+#!/bin/bash
+
+# stolen from http://stackoverflow.com/questions/4156957/merging-branches-without-checkout/4157435#4157435
+
+_usage() {
+ echo "Usage: git merge-ff <branch> <committish-to-merge>" 1>&2
+ exit 1
+}
+
+_merge_ff() {
+ branch="$1"
+ commit="$2"
+
+ branch_orig_hash="$(git show-ref -s --verify refs/heads/$branch 2> /dev/null)"
+ if [ $? -ne 0 ]; then
+ echo "Error: unknown branch $branch" 1>&2
+ _usage
+ fi
+
+ commit_orig_hash="$(git rev-parse --verify $commit 2> /dev/null)"
+ if [ $? -ne 0 ]; then
+ echo "Error: unknown revision $commit" 1>&2
+ _usage
+ fi
+
+ if [ "$(git symbolic-ref HEAD)" = "refs/heads/$branch" ]; then
+ git merge $quiet --ff-only "$commit"
+ else
+ if [ "$(git merge-base $branch_orig_hash $commit_orig_hash)" != "$branch_orig_hash" ]; then
+ echo "Error: merging $commit into $branch would not be a fast-forward" 1>&2
+ exit 1
+ fi
+ echo "Updating ${branch_orig_hash:0:7}..${commit_orig_hash:0:7}"
+ if git update-ref -m "merge $commit: Fast forward" "refs/heads/$branch" "$commit_orig_hash" "$branch_orig_hash"; then
+ if [ -z $quiet ]; then
+ echo "Fast forward"
+ git diff --stat "$branch@{1}" "$branch"
+ fi
+ else
+ echo "Error: fast forward using update-ref failed" 1>&2
+ fi
+ fi
+}
+
+while getopts "q" opt; do
+ case $opt in
+ q ) quiet="-q";;
+ * ) ;;
+ esac
+done
+shift $((OPTIND-1))
+
+case $# in
+ 2 ) _merge_ff "$1" "$2";;
+ * ) _usage
+esac
\ No newline at end of file