#! /bin/sh

# sleep-to -- sleep until a given hour
# $Id: sleep-to,v 1.1 1997/05/20 02:55:54 cdua Exp cdua $
# Carlos Duarte, 970520

USAGE="\
usage: $0 [-h] until-hours

  -h      this help

examples:
   $0 24:00                 sleeps until midnight
   $0 18:00:30              sleeps until 18:00:30
"

while : ; do
	case x"$1" in 
	x-h)	echo "$USAGE"; exit 1 ;;
	x--)	shift; break ;;
	x-?)	echo "invalid option -- `echo $1|cut -c2-`"
		echo "$USAGE"; exit 1 ;;
	*)	break ;;
	esac
	shift
done

if test $# -ne 1; then echo "$USAGE"; exit 1; fi

(echo $1; date; ) | sed '
s/.*\([0-9][0-9]:[0-9][0-9]:[0-9][0-9]\).*/\1/
tb

/[0-9][0-9]*:[0-9][0-9]*:[0-9][0-9]*/ba
/[0-9][0-9]*:[0-9][0-9]*/{;s/$/:0/;ba;}
/[0-9][0-9]*/s/$/:0:0/

:a
s/^/:/
s/$/:/
s/[0-9][0-9]*/0&/g
s/[0-9]*\([0-9][0-9]\)/\1/g
s/^.//
s/.$//

:b
s/:/ 60 60 * * /
s/:/ 60 * + /
s/$/ + /

$a\
-\
p
' | dc | while read x; do 
	sleep $x 
done