# make sure redo doesn't think merely *reading* the old file counts as
# modifying it in-place.
cat $1 >/dev/null 2>/dev/null || true
perl -mTime::HiRes -e '
    $t2 = 1 + int(Time::HiRes::time());
    while (1) {
        $t = Time::HiRes::time();
        last if $t > $t2;
        sleep($t2 - $t + 0.01);
    };
'
cat $1 >/dev/null 2>/dev/null || true
echo hello