A subroutine works, but you should use it a bit differently:

if (arguments_ok(@ARGV)) {
   # do something
} else {
   # complain loudly
}
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You might also be interested in the FindBin core module, which might be more reliable than $0 . ".pl"

Also not that if you want to start another process via system, you should use the LIST form so that spaces in arguments don't confuse your program:

system($^X, "some_script.pl", @ARGV);
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