Find/show merge commits

git-merge-point

#!/bin/bash

usage() {
  echo "git-merge-point <commitid>"
  exit 1
}
[ -n "$1" ] || usage

# Make sure we are in a git directory
git rev-parse --is-inside-work-tree >&- || exit $?

# Get commit name and upstream name
commit="$1"
upstream="${2:-HEAD}"

# Get list merges leading from $commit to $upstream
IFS=$'\n' read -d '' -r -a ancestry < \
  <(git rev-list --ancestry-path --merges "$commit..$upstream" --)

# Get list of merges directly into $upstream
IFS=$'\n' read -d '' -r -a merges < \
  <(git rev-list --first-parent --merges "$commit..$upstream" -- | tac)

# Find merge point
for merge in "${merges[@]}"; do
  for sha in "${ancestry[@]}"; do
    if [ "$sha" = "$merge" ]; then
      echo $sha
      exit 0
    fi
  done
done

echo 'not merged' >&2
exit 1

git-show-merge

#!/bin/bash
usage() {
  echo "git-show-merge <commitid>"
  exit 1
}
[ -n "$1" ] || usage
COMMIT=$(git-merge-point $1)

[ -n "$COMMIT" ] || {
  echo "Not found or never merged"
  exit 1
}

git show --show-signature $COMMIT