get_git_version

#!/bin/bash
VERSION_FILE="GIT_VERSION"
EXEC_PATH="$(which git 2>/dev/null | head -n 1)"
if [ -z "$EXEC_PATH" ]; then
  EXISTS_GITVERSION=0
else
  if [ ! -x "$EXEC_PATH" ]; then
    EXISTS_GITVERSION=0
  else
    EXISTS_GITVERSION=1
  fi
fi

if [ "$EXISTS_GITVERSION" = 1 ]; then
  git describe --always &>/dev/null
  if [ "$?" -ne 0 ]; then
    UNDER_GIT=0
  else
    UNDER_GIT=1
  fi
fi

if [ -r "$VERSION_FILE" ]; then
  EXISTS_FILE=1
else
  EXISTS_FILE=0
fi

if [ "$EXISTS_GITVERSION" = 0 ]; then
  if [ "$EXISTS_FILE" = 1 ]; then
    cat "$VERSION_FILE"
  else
    echo "missing_git_version"
  fi
else
  if [ "$UNDER_GIT" = 1 ]; then
    git describe --always
  else
    if [ "$EXISTS_FILE" = 1 ]; then
      cat "$VERSION_FILE"
    else
      echo "missing_git_version"
    fi
  fi
fi