require-clean-work-tree is a bash script that will prevent you from doing things if your working tree is dirty. It will detect your scm and return false if detection fails or the tree is dirty. Currently it supports only git and mercurial but we can add other scm later like svn or perforce.

require-clean-work-tree

#!/bin/bash
# version: 1.0
# author: Sorin Sbarnea

require_clean_work_tree_git () {
        git rev-parse --verify HEAD >/dev/null || exit 1
        git update-index -q --ignore-submodules --refresh
        err=0

        if ! git diff-files --quiet --ignore-submodules
        then
            echo >&2 "Cannot $1: You have unstaged changes."
            err=1
        fi

        if ! git diff-index --cached --quiet --ignore-submodules HEAD --
        then
            if [ $err = 0 ]
            then
                echo >&2 "Cannot $1: Your index contains uncommitted changes."
            else
                echo >&2 "Additionally, your index contains uncommitted changes."
            fi
            err=1
        fi

        if [ $err = 1 ]
        then
            test -n "$2" && echo >&2 "$2"
            exit 1
        fi
    }


require_clean_work_tree_hg () {
  set -e
  hg pull
  hg update

  hg diff
  # Disallow unstaged changes in the working tree
  if [ -n "$(hg status -mar)" ]
  then
    echo >&2 "error: your index contains uncommitted changes."
    exit 1
  fi
}

LOC=`pwd`

while [ $LOC != '/' ]; do
  if [ -d "$LOC/.git" ]; then
    require_clean_work_tree_git
    break
  elif [ -d "$LOC/.hg" ]; then
    require_clean_work_tree_hg
    break
  else
    LOC=`dirname $LOC`
  fi
done
if [ $LOC == '/' ]; then
  echo >&2 "Unable to detect any .git or .hg repositories."
  exit 1
fi