And if you really don't know which variables might be initialized:

where toto is:

#!/usr/bin/perl -ws
use strict;

{ # you can use -s defined variables here
  no strict 'vars';
  print $var;
}
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Just note that generally -s and use strict; don't go well together. -s should really be used only for throw-away scripts, if not just deprecated, while use strict would be used for everything else. If you use strict you should also use "clean" alternative to -s such as one of the various Getopt::* modules.