I have a script which automates a dump of some discs. As it goes along, it writes to standard output, and I want to log the output by redirecting to a file. Here's a fragement of the script showing the general structure: 
sub perform_dump
{
   print "\nDumping the discs...\n";
   foreach my $disc (@discs) {
      print "...$disc...\n";
      local (*HIS_IN, *HIS_OUT, *HIS_ERR);
      my $cmd  = '/usr/sbin/ufsdump';
      my @args = ('0luf', '/dev/rmt/1n', $disc);
      my $pid  = open3 (*HIS_IN, *HIS_OUT, *HIS_ERR, 
                        $cmd, @args);
      print while (<HIS_ERR>);
      wait;
      
      &barf ('dump-fail', $disc) if $? != 0;
   }
}

[download]
...i.e. run ufsdump in a sub-process, grab the output and channel it to standard out of the perl process. The script works, but each time it print anything, it reprints everything that's been sent to standard output since the start of the programme! Howvere, it only does this with the redirect to the file; writing to the terminal comes out as expected.

Is this a Perl bug, a module bug in IPC::Open3, a feature, or did I just screw up?

In reply to print behaving badly by Anonymous Monk

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