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The problem merlyn is trying to point out is that when you open the file for writing (open (FH, ">file")), you already deleted the contents of the file regardless of any locks. From perlopentut:
    To get an exclusive lock, typically used for writing, you have to be careful. We "sysopen" the file so it can be locked before it gets emptied. You can get a nonblocking version using "LOCK_EX | LOCK_NB".
    use 5.004; use Fcntl qw(:DEFAULT :flock); sysopen(FH, "filename", O_WRONLY | O_CREAT) or die "can't open filename: $!"; flock(FH, LOCK_EX) or die "can't lock filename: $!"; truncate(FH, 0) or die "can't truncate filename: $!"; # now write to FH
Hope that helps!

-- zigdon

In reply to (z) Re: Flock and Destroy by zigdon
in thread First Time Untainting Data by svsingh

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