I had a go at doing it this way using a semaphore file. But I'm running into problems and can't figure out what is wrong. 
sub filelock;

filelock "lockit";

Do the inplace edit stuff here

filelock "unlock";

sub filelock {

 if ( @_ eq "lockit" ) {
         open(LCK,">abc.lock") or die "Can't open abc.lock: $! \n";
         unless (flock LCK, LOCK_EX) {
                warn "Waiting to obtain lock on LCK ....\n";
                flock(LCK, LOCK_EX) or die "Cannot lock semaphore file
+ - $!\n";
         }
 }

 if ( @_ eq "unlock" ) {
        close(LCK)
 }

}

[download]
The problem is that it's not recognising "lockit" or "unlock" when the filelock subroutine is called. Even though when I print out @_ it displays "lockit" or "unlock" accordingly. What am I doing wrong ?

In reply to Re^2: flock on on $^I by Anonymous Monk
in thread flock on on $^I by Anonymous Monk

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