You should check if open was successful, and also if close was: 

open my $output, '|-', $PRINT_CMD
    or die "Can't open pipe to $PRINT_CMD: $!";
print $output $prolog;
...
close $output or warn "Error while closing pipe to $PRINT_CMD: $!";

[download]

Maybe that'll give you some clue about what's wrong.

Perl 6 - links to (nearly) everything that is Perl 6.

In reply to Re: piping to lp is broken after perl upgrade by moritz
in thread piping to lp is broken after perl upgrade by myuserid7

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