bash script to generate change logs from git folder with tagged versions.

changelog.sh

#!/usr/bin/env bash
#
# git change log generator

# https://gist.github.com/bnielsen1965
#
# THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
# EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
# PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
# PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
# NECESSARY SERVICING, REPAIR OR CORRECTION.
#

# default parameters
GIT_PROJECT_PATH=
CHANGE_LOG_PATH=

PACKAGE=`basename $0`


# display usage help
function Usage()
{
  cat <<-ENDOFMESSAGE
$PACKAGE - Generate a change log file from a git project directory.

$PACKAGE [path to project] [path to change log]
arguments:
path to project - the path to the directory that contains the git project
path to change log - the path and filename to use for the generated change log

NOTE: if the path to change log is not specified then the git project directory name and present working path are used.
ENDOFMESSAGE
exit
}


# die with message
function Die()
{
  echo "$*"
  Usage
  exit 1
}


# process command line arguments into values to use
function ProcessArguments() {
  # separate options from arguments
  while [ $# -gt 0 ]
  do
  opt=$1
  shift
  case ${opt} in
  -h|--help)
  Usage;;
  *)
  if [ "${opt:0:1}" = "-" ]; then
  Die "${opt}: unknown option."
  fi
  ARGV+=(${opt});;
  esac
  done

  if [ ${#ARGV[@]} -gt 0 ]; then
  export GIT_PROJECT_PATH=${ARGV[0]}
  fi

  if [ ${#ARGV[@]} -gt 1 ]; then
    export CHANGE_LOG_PATH=${ARGV[1]}
  fi
}


# build environment
function BuildEnvironment()
{
  if [ ! -d "$GIT_PROJECT_PATH" ]; then
    Die "Project path $GIT_PROJECT_PATH does not exists."
  fi

  CWD=`pwd`
  if [ -z "$CHANGE_LOG_PATH" ]; then
    PROJECT_NAME=`readlink -f $GIT_PROJECT_PATH | sed 's#.*/##'`
    CHANGE_LOG_PATH=`readlink -f "$CWD/$PROJECT_NAME.changes"`
  fi
}


function ChangeLog()
{
  cd $GIT_PROJECT_PATH
  CHANGES=`git log --oneline --decorate --color --pretty=format:"%d %s"`

  echo "$CHANGES" | while read line
  do
    if echo "$line" | grep -qP '^\(.*tag:\s+v?[0-9]+\.[0-9]+\.[0-9]+(-[0-9]+)?[^)]*\)'; then
      echo ""
      echo "$line" | sed -rn "s/^\(.*tag:\s+(v?[0-9]+\.[0-9]+\.[0-9]+(-[0-9]+)?).*$/\1/p"
      echo "$line" | sed -rn "s/^\(.*tag:\s+v?[0-9]+\.[0-9]+\.[0-9]+(-[0-9]+)?[^\)]*\)\s*(.*)$/- \2/p"
    else
      echo "- $line"
    fi
  done
  cd $CWD
}



# prepare to execute command
ProcessArguments $*
BuildEnvironment
LOG=$(ChangeLog)
echo "$PROJECT_NAME change log" > "$CHANGE_LOG_PATH"
echo "generated" $(date) >> "$CHANGE_LOG_PATH"
echo "$LOG" >> "$CHANGE_LOG_PATH"