while loop

[azaria]

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[Zaxo]

The logic for that could look something like this:

sub notfree { # returns true if license not free
    # whatever you do with parsing lmstat
}

LOOP: {
    if (notfree @args) {
        sleep $sane_interval;
        redo LOOP;
    }
    else {
        system( @other_args);
    }
}

I'm not entirely clear on what you want, but that should be close. I didn't include the logout part because that doesn't sound right to me. Most unix commands don't do that to the user. Could you describe what you're doing in more detail, so we can understand your requirements better?

[ikegami]

By "logout", I think he means "free the license handle".

[mantadin]

I'm not sure what exactly your question is. Do you want to do something like

while (not &license_free) {
  sleep $a_few_seconds;
}
&execute_command_and_logout;

[blazar]

Well, quite about the only answer that such a question deserves. But while you're there, and the op is clearly a newbie, please do not use the &-form of sub call, since we take care all the time of deprecating it to avoid this cargo-culted remnant from Perl 4 to spread further. If you want to underline that you're doing a sub call, then you may use empty parens...

[mantadin]

Thanks for the info; I did not know that the &-form is considered a cargo-culted remnant.

OTOH, I am not aware of the &-form having any useful advantage. AFAIK, &f, if called from within another sub, is equivalent to f(@_) "but faster", as the camel books states (3rd edition, Chapter 6, scoping issues).