Thanks for the hint so far. I have modified the code, as you suggested. Changed the open to truncate instead of append, and tried using select.

And yes, /tmp/_pid_file contains the PID.
This is fine until I run the script a second time, when /tmp/_pid_file gets truncated even though startup fails.

Any further suggestions? 

# As before ..
# ...
sub main
{
    my $start_mess = "===== Starting $TASK";
    $start_mess   .= " (@_)" if @_;
    $start_mess   .= " =====";
    error( $start_mess );
    my $FH;

    open( HIGHLANDER, ">$PID_FILE") or die( "Cannot write to $PID_FILE
+: $!" );
    {
    my $count = 0;
    {
        flock HIGHLANDER, LOCK_EX | LOCK_NB and last;
        sleep 1;
        redo if ++$count < 3;
        error( "Script is already running." );
            die( "Startup failed, PID file locked." );
        }
     }
    $FH = select(HIGHLANDER);
    $| = 1;
    select($FH);
    print HIGHLANDER $$;

# ..
# ..as before..

[download]

<a href="http://www.graq.co.uk">Graq</a>

In reply to Re: Re: Writing to flock files in a daemon by graq
in thread Writing to flock files in a daemon by graq

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