rel_to_abs.sh

#As readlink is not available on all distro or OSX, provide a portable way to get an 
#absolute path from a relative one.

make_absolute() {
  local ret=false
  local rel_path=$1

  if [[ ! -z $rel_path ]]; then
    #strip eventual last slash
    rel_path=${rel_path%/}

    if [ "$rel_path" = "" ]; then
      rel_path="/"
    fi

    base_name=${rel_path##*/}
    rel_dir=${rel_path%$base_name}

    if [[ $rel_dir = "" ]]; then
        rel_dir="."
    fi

    if cd -P "$rel_dir" 1>/dev/null; then
      #we jump in the directory and use $PWD
      if [[ $(pwd) = "/" ]]; then
        echo "/$base_name"
      else
        echo "$(pwd)/$base_name"
      fi

      cd - 1>&2 > /dev/null #get back to OLD_PATH
      ret=true
    fi
  fi

  $ret
}