unixorn/git-extra-commands

#!/usr/bin/env bash
# Author: Mislav Marohnić  <mislav.marohnic@gmail.com>
# https://github.com/mislav/dotfiles
#
# Shows git commits since the last tagged version. If library code appears to
# be contained in `lib` or `libexec` directories, show changes pertaining to just that code.
set -e

paths=""
num_libfiles="$(git ls-files -- lib libexec | wc -l)"
if [ "$num_libfiles" -gt 0 ]; then
  paths="bin lib libexec"
fi

format='%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%ar)%Creset'

show_log() {
  git log --graph --format="$format" ${1:+${1}..} -- "$paths"
}

desc="$(git describe --tags HEAD 2>/dev/null)" || {
  echo "no releases exist; showing all changes"
  show_log
  exit
}

# check for "<tag>-<num_commits>-<sha>" format
if [[ "$desc" == *-*-g* ]]; then
  tag_with_num="${desc%-*}"
  num_commits="${tag_with_num##*-}"
  tag="${tag_with_num%-*}"
else
  num_commits=0
  tag="$desc"
fi

if [ "$num_commits" -gt 0 ]; then
  echo "${num_commits} commits since ${tag}"
  show_log "$tag"
else
  echo "no commits since ${tag}"
fi