don't emit STDERR output without DEBUG envirment variable

diff --git a/scripts/aleph2iso.pl b/scripts/aleph2iso.pl
index 7b8df6b..b058008 100755 (executable)
--- a/scripts/aleph2iso.pl
+++ b/scripts/aleph2iso.pl
@@ -10,6 +10,8 @@ my $source = shift @ARGV || die "usage: $0 file.m21\n";
 my $dest = $source;
 $dest .= '.iso';
 
 my $dest = $source;
 $dest .= '.iso';
 

+close(STDERR) unless $ENV{DEBUG};
+

 open(my $m21, '<', $source);
 open(my $out, '>:encoding(utf-8)', $dest);
 
 open(my $m21, '<', $source);
 open(my $out, '>:encoding(utf-8)', $dest);