#!/bin/rc
# E file - B file, wait until it changes, exit
rfork e
if (! ~ $#* 1) {
	echo usage: $0 file >[1=2]
	exit usage
}
if (! test -e $1) {
	echo $0: $1: no such file >[1=2]
	exit no-file
}
otm = `{mtime $1 | awk '{print $1}'}
B $1
while (~ $otm `{mtime $1 | awk '{print $1}'})
	sleep 1
exit ''