Maybe I'm overlooking something, but given the following example code, it is not clear to me where there could occur a race condition.

#! /usr/bin/perl                                                      
+                                   
use strict;
use warnings;

my $pidfile="testfile.pid";
my $scriptname = $0;
my $pid="$$";

if(-e $pidfile)
{
    open(PFH, '<', $pidfile) or die $!;
    $pid =<PFH>;
    close(PFH);
    print"$scriptname already running: pid is $pid";
    exit;
}

open(PFH, '>', $pidfile) or die $!;
print(PFH $$);
close(PFH);

# do the job                                                          
+                                   
sleep 13;

unlink($pidfile);

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In reply to Re^3: Mechanism for ensuring only one instance of a Perl script can only run? by rizzo
in thread Mechanism for ensuring only one instance of a Perl script can only run? by redapplesonly

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