Redirect to STDOUT and file

stevendel has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to redirect STDOUT and STDERR to a file as well as to STDOUT or STDERR (depending on the intended destination). I am familiar with IO::Tee, so what's the problem? I want to write this in such a way that any messages, including runtime errors thrown by modules outside of my control, are sent to both places. The snippet below should show what I am looking for (and what has failed for me thus far):

use IO::Tee;
use IO::File;

open(OLDOUT, ">&STDOUT");
open(OLDERR, ">&STDERR");
my $output_file = new IO::File(">tt1.out");
my $TeeOut = new IO::Tee(\*OLDOUT, $output_file);
my $TeeErr = new IO::Tee(\*OLDERR, $output_file);

open(STDERR, ">&", \*$TeeErr);
select(STDERR); $| = 1;
print $TeeErr "This goes to both STDERR and to the file.\n";
print STDERR "I would like this to do the same as above, but it goes n
+owhere.\n";
[download]

Any thoughts/suggestions?

Comment on Redirect to STDOUT and file Download Code

Replies are listed 'Best First'.
Re: Redirect to STDOUT and file by ikegami (Patriarch) on Jan 10, 2008 at 05:30 UTC
This post explains pilcrow's solution. `open '>&'` creates a duplicate of a system file handle. `tie` doesn't create a system file handle, just a Perl one, so it can't be duplicated using `open '>&'`. However, Perl handles can be duplicated. Simply use the assignment operator. In general: `DST = SRC{IO};` In this case: `STDERR = $TeeErr{IO};` `open '>&'` is normally preferred because child processes can inherit the resulting handle. However, since IO::Tee doesn't create a real (system) file handle, neither the original nor the copy can be inherited by child processes.	[reply] [d/l] [select]
Re: Redirect to STDOUT and file by pilcrow (Sexton) on Jan 09, 2008 at 18:19 UTC
`open(STDERR, ">&", \$TeeErr);` This line doesn't do what you think. I suspect you've got a file named something like IO::Tee=GLOB(0x123456) on your system, with the output you desire. Something like `STDERR = $TeeErr` comes closer to what you want, but isn't perfect. The surest way to trap and tee all of a program's output is, it seems to me, external: simply run the code piped to a teeing process. -Mike	[reply] [d/l] [select]
Re^2: Redirect to STDOUT and file by ikegami (Patriarch) on Jan 10, 2008 at 05:19 UTC
`open` isn't going to create a file (named `IO::Tee=GLOB(0x123456)` or anything else) when it wasn't asked to create a file. It returns the error "Invalid argument".	[reply] [d/l] [select]
Re^3: Redirect to STDOUT and file by pilcrow (Sexton) on Jan 10, 2008 at 21:54 UTC
open isn't going to create a file (named IO::Tee=GLOB(0x123456) or anything else) when it wasn't asked to create a file. It returns the error "Invalid argument". Not for me under 5.8.8: `$ ls $ perl -Mstrict -MIO::Tee -le 'my $tee=IO::Tee->new(">/dev/null"); ope +n(FH, ">&", \*$tee)' $ ls IO::Tee=GLOB(0x8802e2c) $ perl -e 'printf "%vd\n", $^V' 5.8.8` [download]	[reply] [d/l]
Re^4: Redirect to STDOUT and file by ikegami (Patriarch) on Jan 12, 2008 at 05:28 UTC
Re: Redirect to STDOUT and file by alexm (Chaplain) on Jan 09, 2008 at 18:46 UTC
File-Tee seems quite simpler and meets your needs too. Since your specially interested in teeing STDOUT and STDERR, I think you'll find File::Tee a lot easier to use.	[reply]
Re: Redirect to STDOUT and file by stevendel (Novice) on Jan 09, 2008 at 19:18 UTC
File::Tee works very well for me on Unix. Unfortunately, I would like this to work on Windows, too, and even with Cygwin, it does not quite work (it does not capture the output of subprocesses).	[reply]
Re: Redirect to STDOUT and file by absolut.todd (Monk) on Jan 10, 2008 at 01:51 UTC
I had a similar problem earlier in the year. See How to log all output from a program?	[reply]
Re: Redirect to STDOUT and file by starbolin (Hermit) on Jan 09, 2008 at 20:09 UTC
See 535209 s//----->\t/;$~="JAPH";s//\r<$~~/;{s\|~$~-\|-~$~\|\|\|s \|-$~~\|$~~-\|\|\|s,<$~~,<~$~,,s,~$~>,$~~>,, $\|=1,select$,,$,,$,,1e-1;print;redo}	[reply] [d/l]


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