#!/bin/sh
#
# x-until-error: Repeatedly execute a command until it fails (non-zero exit status)
#
# Description:
#   This script executes the given command repeatedly until it returns a non-zero
#   exit status. It always runs the command at least once.
#
# This script is based on the original work by Steve Kemp.
# Original work Copyright (c) 2013 by Steve Kemp.
#
# The code in the original repository may be modified and distributed under your choice of:
#   * The Perl Artistic License (http://dev.perl.org/licenses/artistic.html) or
#   * The GNU General Public License, version 2 or later (http://www.gnu.org/licenses/gpl2.txt).
#
# Modifications and enhancements by Ismo Vuorinen on 2025.
#
# Usage:
#   x-until-error [--sleep SECONDS] command [arguments...]
#
# Options:
#   --sleep SECONDS    Wait SECONDS (default: 1) between command executions.
#   -h, --help         Display this help message.
#
# Example:
#   x-until-error --sleep 2 ls -l

# Default sleep interval between executions.
SLEEP_INTERVAL=1

# Function to display usage information.
usage()
{
  cat << EOF
Usage: $0 [--sleep SECONDS] command [arguments...]

Repeats the given command until it fails (returns a non-zero exit status).

Options:
  --sleep SECONDS    Wait SECONDS (default: 1) between command executions.
  -h, --help         Display this help message.

Example:
  $0 --sleep 2 ls -l
EOF
  exit 1
}

# Parse command-line options.
while [ $# -gt 0 ]; do
  case "$1" in
    --sleep)
      shift
      if [ $# -eq 0 ]; then
        echo "Error: --sleep requires a numeric argument." >&2
        exit 1
      fi
      SLEEP_INTERVAL="$1"
      shift
      ;;
    -h | --help)
      usage
      ;;
    --) # End of options marker.
      shift
      break
      ;;
    -*)
      echo "Error: Unknown option: $1" >&2
      usage
      ;;
    *)
      break
      ;;
  esac
done

# Ensure a command is provided.
if [ $# -eq 0 ]; then
  echo "Error: No command specified." >&2
  usage
fi

# Execute the command repeatedly until it fails.
while true; do
  "$@"
  status=$?
  if [ $status -ne 0 ]; then
    exit $status
  fi
  sleep "$SLEEP_INTERVAL"
done