run_once.bash - run command only once

run_once.bash

#!/usr/bin/env bash
#
# run_once.bash - run command only once
# Copyright (c) 2019 Koichi OKADA. All right reserved.
# This script distributed under the MIT license.
#

function run_once () # [<command> [<args> ...]]
# Run [<command> [<args> ...]] only once.
# Return:
#   Return exit status which was returned first time call for [<command> [<args> ...]].
{
  declare -gA RUN_ONCE
  declare -n retval=RUN_ONCE[$(IFS=$'\x1c'; printf "%s" "$*")]
  [ -z "$retval" ] && { "$@"; retval=$?; }
  return $retval
}

[ "$(readlink -f -- "$0")" = "$(readlink -f -- "$BASH_SOURCE")" ] && echo "Usage: source run_once.bash"