#!/bin/sh -e
# POSIX shell variant for ubase respawn

usage() {
    printf 'usage: %s [-d N] cmd [args...]\n' "${0##*/}"
    exit "${1:-0}"
}

die() { printf '%s\n' "$@" >&2; exit 1;}

case "$1" in
    -d) [ "$3" ] || usage 1
        [ "$2" -gt 0 ] || die "Not a number: $2"
        delay=$2; shift 2
        ;;
    --help|-h|'') usage ;;
    -*) usage 1
esac

while :; do
    "$@"
    [ "$delay" ] && sleep "$delay"
done