Subject: B20: Strange intermittent globing bug? File locking?.
From: [email-masked] (BAARDA, Don)

24 Nov 1998 07:56:41 -0800
Message-ID: <098D75523766D111AAA300805FF59873081585.cygnus.gnu-win32@MDNTEX1>
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To: "[email-masked]'" <[email-masked]>

G'day all,

I've found some weird behaviour that I thought was some vestigial failed
hack attempts to get less working with bash.

Back in the B19 days I created my own "less" command that fired up notepad.
When I upgraded to B20 it broke, but in a weird way. It would lock up before
starting notepad, and only ^C would return me to the prompt. Then I changed
the name to "less.old" and it worked (mv less less.old). Then I moved it
back to less and it locked up. Then I moved it to "l" and it still locked up
(kill the hack attempts for "less" theory). These problems appeared to be
definitely repeatable, and I thought I could pin it down to a globing
problem for filenames without a period in them. The script looked like;

#!/bin/sh
TEMPFILE=$TEMP\\$$.tmp
cat "$@" > $TEMPFILE
(notepad $TEMPFILE ; rm $TEMPFILE) &

Then I started playing with the code, commenting out lines and adding
echo/cat things. The problems persisted, with no output before the lockup,
even when the script was reduced to the following;

#!/bin/sh
TEMPFILE=$TEMP\\$$.tmp
echo "$@"
cat "$@"
#cat "$@" > $TEMPFILE
#(notepad $TEMPFILE ; rm $TEMPFILE) &

At some point, the problem mysteriously stopped, and I my once repeatable
problem stopped repeating. I have no idea why it stopped. The four lines of
script are unchanged AFAIK, and I can call it anything and it works. The
only theories I have are that maybe there was a hidden control character
buried in the script that my editing removed, or "something else" happened.
Maybe the fact that I was running it with itself as a parameter was
intermittently (or rather consistently) hitting some file locking problem?

While the problem was there, I repeatedly demonstrated the problem by "mv
less less.old; less.old less.old; it works" and "mv less.old less; less
less; it locks up" over two days and multiple attempts. I also repeatedly
checked "type less" to make sure I was running what I thought I was. I also
added and removed the "debug" code a few times over the two days and it
still seemed repeatable. I only experimented with names other than "less"
and "less.old" towards the end, which revealed that using the name "less"
was not necessarily the culprit, but other names also had the problem. Just
as I was trying to characterise what names did and didn't work, the problem
went away.

I'm glad it now works, but I'm really puzzled and slightly worried by
whatever it was. Maybe it's some text vs binary mode feature?

Don
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