in reply to How to log all output from a program?

Is redirecting STDOUT and STDERR of the invoking shell an option? 
(perl -le 'print "foo"; print STDERR "bar"' | sed 's,^,OUT ,' | tee -a
+ log.stdout ) 2>&1 1>/dev/tty | sed 's,^,ERR ,' | tee -a log.stderr

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Of course that doesn't work if there's no tty.

update: replace /dev/tty with /dev/null in that case. Or better, if you don't need output to the terminal 

(perl -le 'print "foo"; print STDERR "bar"' | sed 's,^,OUT ,') 2>&1 1>
+>log.stdout | sed 's,^,ERR ,' >> log.stderr

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--shmem 

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

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Re^2: How to log all output from a program?
by salva (Canon) on Oct 15, 2007 at 08:25 UTC
    you can do he same from perl: 
    my $pid = open STDOUT, '|-';
unless ($pid) {
  defined $pid or die "unable to fork new process: $!";
  open my $tee, '>>', $stdout_log_fn
    or die "unable to open '$stdout_log_fn'";
  select $tee; $| = 1;
  select STDOUT; $| = 1;
  while (<>) {
    print $tee "OUT $_";
    print $_;
  }
  exit(0);
}

# and repeat for STDERR

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[reply]
[d/l]
      Ah, of course. But you also can do that from the outside :-)

      BTW, if you open/close the filehandle inside the loop (and perhaps include $$ in the output) it is less probable that multiple processes mess up the logfiles.

      --shmem 

      _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
[reply]
        BTW, if you open/close the filehandle inside the loop (and perhaps include $$ in the output) it is less probable that multiple processes mess up the logfiles

        I don't think so. Usually, the OS provides atomic write operations up to a certain length. If your write operations go over that limit, the way to ensure that data from different processes does not interleave is to lock the file.

        Reopening the file on every write allows to rotate the logs from the outside without the current script knowing.

[reply]
      BTW, I have just released to CPAN File-Tee that's an augmented version of the code above.
[reply]

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