ww and wu - wait while/untill (was: DistantBiff)

[Amos Shapir]

The idea of DistantBiff is to run a command agin and again until
something happens; here's a shell file that can do thi with any command.

Call it 'ww' to run the command until its output changes, and link to 'wu'
to run until its output stops changing.  I have found it very useful.

Flags:
	-t time - run every 'time' seconds (default 60)
	-v - view output of each iteration (obviously only useful to 'wu')
	-x [time] - run on 'time' seconds after the exact time
		(i.e. -t 3600 -x 1200 runs the command on the hour+20 mins.)


		o /		o /		o /		o /
--Cut-here-------X---------------X---------------X---------------X----
		o \		o \		o \		o \

: wait while/until
case $0 in
*u)	r='!='; o=x;;
*w)	r='=';;
esac
intrval=60
for i
do
	case $i in
	-t)	intrval=$2; shift;;
	-v)	view=$i; shift;;
	-x)	case "$2" in
		[0-9]*)	exact=$2;;
		*)	exact=0;;
		esac
		shift;;
	[0-9]*)	shift;;
	*)	break;;
	esac
done
cmd="$@"
n=`eval "$cmd"`
o="$n"$o
echo "$n"
while [ "$n" $r "$o" ]
do
	slp=$intrval
	case $exact in
	?*)	d=`date`
		slp=`expr $intrval - \( \( "$d" : '.*\(..\):..:' \* 60 \
		+ "$d" : '.*:\(..\):'  \) \* 60 + "$d" : '.*:..:\(..\)' \) \
		% $intrval + $exact`
	esac
	sleep $slp
	o="$n"
	n=`eval "$cmd"`
	case $view in
	-v)	echo "$n";;
	esac
done
case $view in
-v)	: ;;
*)	echo "$n";;
esac
echo -n 

		o /		o /		o /		o /
--Cut-here-------X---------------X---------------X---------------X----
		o \		o \		o \		o \
May the Source be with you, always...
-- 
	Amos Shapir		amos at taux01.nsc.com, amos at nsc.nsc.com
National Semiconductor (Israel) P.O.B. 3007, Herzlia 46104, Israel
Tel. +972 52 522261  TWX: 33691, fax: +972-52-558322 GEO: 34 48 E / 32 10 N