Date: Wed, 03 Feb 1999 23:31:34 +0200 From: Sheldon Hearn <axl@iafrica.com> To: Robert Wall <rsw@vsat.net> Cc: security@FreeBSD.ORG Subject: Re: Perl and file locking Message-ID: <51845.918077494@axl.noc.iafrica.com> In-Reply-To: Your message of "Wed, 03 Feb 1999 12:29:07 CST." <Pine.BSF.3.96.990203122205.27616A-100000@bridge.millstream.net>
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On Wed, 03 Feb 1999 12:29:07 CST, Robert Wall wrote:
> I noticed something interesting the other day - I'm writing a perl script
> to add users to my master.passwd file, and I'm attempting to use exclusive
> locks (flock filename, 2). During my test run of the script, another
> program was accessing the file. My program paused and stuck until it
> could get the exclusive lock for the file (~20 seconds), then finished
> executing normally. Is this a bug, a feature, or just general weirdness?
You need your lock attempt to be non-blocking:
use Fcntl ':flock';
flock(HANDLE, LOCK_EX | LOCK_NB) or
warn("Can't lock right now, will try again soon\n");
See flock(2) and perlfunc(1).
Ciao,
Sheldon.
PS: Your question should really have gone to a perl-specific list,
rather than a freebsd-specific list.
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