Answer: Re: Make a perl script self aware...

Fellow Monks,

the following is the solution I choose the problem described above.

I did use demerphq's code, removed the indirect filehandles and commented it for maintenance reasons.

BTW: demerphq, is there a reason for the use of indirect filehandles? The script works without them, and it's a lot easier to maintain without them.

As demerphq noted before... the DIE is mute on Windows most of the time.

Final Code:

    # Needed for "Only allow one process of this script"-rule
    use Fcntl ':flock';
    
    INIT
    {
        open  LH, $0 
            or die "Can't open $0 for locking!\nError: $!\n";
        # lock file so that it can only be accessed 
        # by the current running script
        # DIE is mute (doesn't print to the screen) on Windows
        flock LH, LOCK_EX|LOCK_NB
            or die "$0 is already running somewhere!\n";
    }
[download]

Thanks for all your help, you are the monks that make this a great community.

/neuroball/

Comment on Answer: Re: Make a perl script self aware... Download Code

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Make a perl script self aware... all platforms by monkeyperl (Initiate) on Jun 25, 2008 at 00:51 UTC
This is an interesting problem indeed. I have used this method of opening the script itself and placing an exclusive lock on it for quite sometime, without problems However, I have started working with Unix AIX recently and the solution no longer works :( I had never had any problems with several Linux distros, FreeBSD, Mac OS X or Windows. But sadly under AIX the script fails to get a lock on itself, weather it is running or not. I added a $! to the flock like so: `flock LH, LOCK_EX\|LOCK_NB or die "$0 is already running somewhere!\n$!";` [download] and the OS error message is: A file descriptor does not refer to an open file Interesting, the error message reads as if the file open failed, and yet it was fine as far as I can tell because the 'or die' for open did not get invoked... odd. Any suggestions?	[reply] [d/l]

Replies are listed 'Best First'.

Make a perl script self aware... all platforms
by monkeyperl (Initiate) on Jun 25, 2008 at 00:51 UTC

flock LH, LOCK_EX|LOCK_NB
            or die "$0 is already running somewhere!\n$!";
[download]

[reply]
[d/l]