Keep in mind you can't use LOCK_UN safely because of buffering. Use close() for that.

Is that still true--I asked in total ignorance--given this from perlfunc:flock?

To avoid the possibility of miscoordination, Perl now flushes FILEHANDLE before locking or unlocking it.

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller
If I understand your problem, I can solve it! Of course, the same can be said for you.

Huh. That's what I last read from Mr. Documentation. I dunno. Maybe he knows better.

use Fcntl qw(:DEFAULT :flock);
$lockfile = "counter.lck";
sysopen(COUNTERLOCK, $lockfile, O_RDONLY | O_CREAT) or die "can't open
+ $lockfile: $!";
flock(COUNTERLOCK, O_EXCL) or die "can't lock $lockfile: $!";
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don't unlock the counterfile/lockfile, just close them. this flushes the buffers and releases locks and closes in a fairly atomic fashion....that's another bug in the original code.

Modern versions of Perl flush file buffers before locking or unlocking a file. This is even documented.

Abigail

I don't quite understand why to use sysopen. The same trouble Gorby has now, I had about two years ago (CGI counter resets for no obvious reason). Later I modified my counting system to something similar to your example. It obviously works, but if it's "bad" code I surely want to understand why and improve it. Here it is:

#! /usr/bin/perl

use Fcntl ':flock';
open(Z,"+<count.txt")||&neu;
flock(Z,LOCK_EX); $z=<Z>; $z++;
seek (Z,0,0); print Z "$z\n"; flock(Z,LOCK_UN); close(Z);
print "Status: 204 No Response\n\n";
exit(0);

sub neu {open(Z,">count.txt"); print Z "0\n"; close(Z); open(Z,"+<coun
+t.txt");}
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