An automatic backup of bashrc on load bash and after 10 minutes from the last edit of .bashrc

bashrc_autobackup.sh

# START AUTOBACKUP .bashrc
how_old_is_file_from_now() {
  if [[ ! -r $1 ]]; then
    echo 0
  else
    echo "$(($(date +%s) - $(date -r "$1" +%s)))"
 fi
}

bak_have_same_modify_date() {
  if [[ ! -r "$1".bak ]]; then
#    echo "File .bak does not exist"
    return 0
  fi

  if [[ "$(date -r "$1" +%s)" == "$(date -r "$1".bak +%s)" ]]; then
    return 0
  fi
  return 1
}

bashrc="$HOME/.bashrc"
if [[ -r "${bashrc}" ]] && ! bak_have_same_modify_date "$bashrc"; then
  how_old_is_bashrc=$(how_old_is_file_from_now "$bashrc")
  if [[ ${how_old_is_bashrc} -gt 600 ]]; then
    echo "Backup bashrc"
    cp -a "${bashrc}" "${bashrc}.bak"
  fi
fi
# END AUTOBACKUP .bashrc