citycrew has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,

Is there a way to send a signal to a script and have it restart itself?

I have a utility script that is always running. When I update the script on the server, I want to be able to send a SIG to it and have it restart itself and load the new changes. It runs as a different user so it's a bit of a pain to su to root and kill it manually, plus I want to trigger that reload from another script when it is updated.

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Re: Restarting same script
by jwkrahn (Abbot) on Dec 27, 2011 at 21:57 UTC
    Is there a way to send a signal to a script and have it restart itself?

    Yes there is.    A lot depends on what you mean by "restart itself".    The simple answer is exec $0;.    And the usual daemon behavior is to reset on a SIGHUP signal.

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      You'll have better luck with: 

      exec $^X, $0, @ARGV
    or  die "Can't restart self: $!\n";

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      Other hints: Don't destroy @ARGV when you process it. Have the signal handler set a global that the main loop checks for so the exec doesn't interrupt some unfinished operation. It can be wise to have a long-running Perl process do this on a regular schedule even without having to be given a signal as it can reduce the impact of whole classes of bugs that you are unlikely to ever run into other than with a very long-running process.

      See %SIG. Sadly, that bit of documentation doesn't appear to contain the very useful link that is included at the bottom of the kill documentation (so also follow my last link so you can follow its last link as well).

      - tye        

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Re: Restarting same script
by citycrew (Acolyte) on Dec 31, 2011 at 05:39 UTC

    Thanks for the reply guys, I'll have a play with that and see how it all works out.

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