gistfile1.sh

#!/bin/sh
#
# Generates version.h in all app_* directories
# If filenames are supplied on the command line, create those instead.
# If a directory is supplied on the command line, output the version of that directory

# Determine if git can provide a sensible version string
have_version() {
  git describe >/dev/null 2>&1 && return 0
  return 1
}


#
# Return the last commit to a given directory/file
#
commit() {
  git log --max-count=1 --pretty=format:%H "${1}"
}

#
# Print a string which describes this version of the repo
# If run outside of a git repo (have_version returns non-zero), do nothing
# $1: a directory to date. If empty, uses .
version() {
  local DIR=$1
  [ -z "$DIR" ] && DIR="."

  local LAST_COMMIT=$(commit ${DIR})
  have_version && git describe --always "${LAST_COMMIT}"
}


# Print a date and time
timestamp() {
  date +%y%m%d-%H:%M:%S
}

# Create C header with filename provided by $1
# If no version information is available, creates file
# but does not clobber.
# The created file defines the VERSION macro as a const char[]
create_file() {
  local FILENAME=$1
  [ -z "$FILENAME" ] && return

  local TIMESTAMP=$(timestamp)

  if have_version; then
    local DIRNAME=$(dirname "${FILENAME}")
    local TAG=$(version "${DIRNAME}"       | sed -re 's/([^-]*).*/\1/')
    local REVISIONS=$(version "${DIRNAME}" | sed -re 's/([^-]*)-?//' | sed -re 's/([0-9]+).*/\1/')
    local COMMIT=$(commit "${DIRNAME}")

    # The tag is something like 0.2
    local VERSION=${TAG}

    # Add the potential number of commits since the tag, making 0.2.26
    [ -n "${REVISIONS}" ] && VERSION="${VERSION}.${REVISIONS}"

    [ -z "${VERSION}" ] && VERSION="0.0.1"

    echo "#define VERSION \"${VERSION}\"" > ${FILENAME}
    echo "#define BUILD_TIME \"${TIMESTAMP}\"" >> ${FILENAME}
    echo "#define BUILD_COMMIT \"${COMMIT}\"" >> ${FILENAME}
  else
    if [ ! -f "${FILENAME}" ]; then
      echo "#define VERSION \"unknown\"" > ${FILENAME}
      echo "#define BUILD_TIME \"${TIMESTAMP}\"" >> ${FILENAME}
      echo "#define BUILD_COMMIT \"${VERSION_STRING}\"" >> ${FILENAME}
    fi

  fi

}

if [ -z "$1" ]; then
  # Nothing specified, create app_*/version.h
  ROOT=$(dirname "$0")

  for APPDIR in ${ROOT}/app_*/; do
    create_file ${APPDIR}/version.h
  done

else
  # One or more explicit file/directory names specified
  for VERSION_ARG in "${@}"; do
    # That's a directory, output its version
    if [ -d "${VERSION_ARG}" ]; then
      version ${VERSION_ARG}
    else
      # It's a file to be created
      echo "Creating ${VERSION_ARG}"
      create_file "${VERSION_ARG}"
    fi
  done
fi
~