sub usage {
   print STDERR $_[0] if @_;
   print STDERR "usage: ...\n";
   exit(1);
}

GetOptions(\%opt,
   'shell=s',
   'foo=s',
   'bip',
   'bar',
   'baz'
)
   or usage();

defined($opt{input})
   or usage("Argument 'input' is required\n");

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In reply to Re: non-option argument question by ikegami
in thread non-option argument question by dr_jkl

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