Date: Mon, 21 Dec 1998 21:43:24 -0500 (EST) From: Thomas David Rivers <rivers@dignus.com> To: freebsd-hackers@freefall.cdrom.com Subject: Interesting un-interruptible shell script on 3.0-RELEASE (possible sh bug?) Message-ID: <199812220243.VAA21066@lakes.dignus.com>
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Try the following on a 3.0-RELEASE system, under the bourne shell:
while true
do
sleep 2
done
You'll quickly discover there's no way to interrupt it (i.e. control-C
if that's your intr character.)
But, individually, the two ideas (the while loop and the sleep) are
quite interruptable.
That is, you can interrupt this:
while true
do
done
And, you can interrupt this:
sleep 10
But, I can't interrupt the combination; even when I hold down control-C
(which, should eventually be in the 'right place at the right time' to
interrupt the sleep followed by another control-C to interrupt the while
loop. Even a ^\ (my quit character) won't stop the loop; it does get
sleep to dump core.. but the loop quickly (too quickly apparently) starts
up another sleep.
I'd have to guess it to be a shell bug... seems like it could affect
trap behaviour as well.
This "interesting" phenomenon doesn't seem to be present on a 2.2.X system.
Could some other people with 3.0 (RELEASE or later) try it out... if it's
a consistent problem; I'll submit a pr on it.
- Dave Rivers -
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