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    my $filename= $param =~ m#^(\w[-.\w]*)\z#
      or  die "Invalid file name ($param).\n";

    my $filepath= $param =~ m#^((?:/?[.\w][-.\w]*)+)\z#
      or  die "Invalid file path ($param).\n";

#!/usr/bin/perl -w
use strict;
...
    }
    return catpath( $vol, $dirs, $file );
}