Run a command at a certain time. Simpler than at(1) - it creates a background job in the current shell environment.

alarm

#!/bin/bash

if [ "$#" -lt 2 ]; then
	echo "USAGE: $0 TIME COMMAND {ARGS}"
	echo "Run COMMAND with ARGS at specified TIME."
	echo "TIME may be given in any form understood by date(1)"
	exit 2
fi

duestr="$1"
shift

due=`date -d "$duestr" +%s`
if [ ! "$due" ]; then
	echo "Error: Could not understand due time."
	exit 1
fi
now=`date +%s`
interval=$((due - now))

if [ "$interval" -lt 0 ]; then
	echo "Error: $durstr is $((-interval))s in the past."
	exit 1
fi

( sleep "$interval" && "$@" ) &