DIR is the real directory of this script

script.sh

SOURCE="${BASH_SOURCE[0]}"
# resolve $SOURCE until the file is no longer a symlink
while [ -h "$SOURCE" ]; do
  TARGET="$(readlink "$SOURCE")"
  if [[ $SOURCE == /* ]]; then
    SOURCE="$TARGET"
  else
    DIR="$( dirname "$SOURCE" )"
    # if $SOURCE was a relative symlink, we need to resolve it relative
    # to the path where the symlink file was located
    SOURCE="$DIR/$TARGET"
  fi
done
RDIR="$( dirname "$SOURCE" )"
DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"