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

Hi there,

I have a script which partitions a large set of files into sets of approx. equal (byte) size and then executes a command for each of the sets using system. The problem I have now is that sometimes even the subsets are so large that I exceed the max. number of arguments the shell supports. I'd like to change this, but I can't find out what the max number of arguments is! Is there any variable / function / module to get this information?

OK, so this is more of a shell question than a perl question, but anyway....

Thanks,

pike

P.S.: I have to keep track how many commands I submitted, so using  xargs is not an option...

Replies are listed 'Best First'.
Re: max number of arguments
by Zaxo (Archbishop) on Sep 05, 2002 at 09:02 UTC

    It may help to bypass the shell by calling system with list syntax:

    my $result = system '/path/to/program', $flags, @bigarray;

    [download]
    You don't say what system call you're running, but it could have limits of its own. Check the return value to see what happened.

    After Compline,
    Zaxo

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[d/l]
      I'm running RedHat linux - and I use bash as my logon shell. Is there any environment variable that contains the max length of the command line? Or any other way to get it?

      pike

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Re: max number of arguments
by PodMaster (Abbot) on Sep 05, 2002 at 09:02 UTC
    You'd really need to consult your shell's documentation. There really isn't a limit on the number of arguments you can pass, but more the length. This isn't always easy to track down in documentation (especially if it isn't documented).

    I suggesting reading the arguments off of stdin, by simply fireing off a system(qw{ ./foo < foo.args })

    Either that or use something like DB_File, and pass arguments that way. You can keep things simple this way (simple enough)

    update:
    IIRC, there is also a module on cpan which would let you circumwent any shell argument size limits, but it may be just a figment of imagination (it might be Argv I was thinking off, but it doesn't matter, it appears Zaxo is correct).

    update:
    Great Zaxo, if that indeed is true ;)

    ____________________________________________________
    ** The Third rule of perl club is a statement of fact: pod is sexy.

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Re: max number of arguments
by MZSanford (Curate) on Sep 05, 2002 at 15:41 UTC
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