You are right that does work as expected, because you aren't running a system() or
exec() or backticks command in there. Try adding system("xcopy"), which will produce
one STDOUT and one STDERR line. You will notice that the STDERR line goes to the file
as it should, but the STDOUT line still prints to the screen even though it should
print to the file.
This works fine on *nix machines, but fails on Win2k and NT. I am assuming it is a
problem with the fork implementation, which is experimental, but there has got to be a
workaround!!
Help!
Nathan
-----Original Message-----
From: $Bill Luebkert [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, July 09, 2002 6:40 PM
To: Goff, Nathan
Cc: '[EMAIL PROTECTED]'
Subject: Re: Fork, system and STDOUT redirection
Goff, Nathan wrote:
> Below is a simple example of a more complex mulit-platform perl script
> that I have written. Basically, a child process(thread) needs to be
> able to redirect STDOUT and STDERR to files. When the child process
> does so in the script below I get STDERR & STDOUT print statements in
> the files, but the STDOUT from the system command still goes to the
> screen. The STDERR seems to go correctly to the file. I was able to
> dig up a bug report that described a similar problem. Is there a
> version of activeperl that fixes this problem? If not, is there a
> workaround?
>
> It only happens when the fork() call is involved and it works properly
> when I use the cygwin port of perl.
>
> I have tried it on activeperl 5.6.1 build 628 & 633.
>
> Thanks,
>
> Nathan Goff
> Build Engineer
> Mentor Graphics Corp
>
> $SIG{'CHLD'} = 'IGNORE';
> $ERR_FILE = "c:\\tmp\\err.txt";
> $OUT_FILE = "c:\\tmp\\out.txt";
>
> unlink($ERR_FILE);
> unlink($OUT_FILE);
>
> while(TRUE)
> {
> #print STDOUT "parent\n";
> #print STDERR "parent\n";
> #open(SAVEOUT, ">&STDOUT");
> #open(SAVEERR, ">&STDERR");
>
> close(STDOUT);
> close(STDERR);
You're closing STDOUT/ERR here which means you can't get them back in run.
> $pid1 = fork();
>
> if($pid1 == 0)
> {
> run();
> exit(0);
> }
>
> sleep(5);
> }
>
>
> sub run
> {
> open(SAVEOUT, ">&STDOUT");
> open(SAVEERR, ">&STDERR");
STDOUT and STDERR are already closed from main routine.
> open(STDERR,">>${ERR_FILE}");
> open(STDOUT,">>${OUT_FILE}");
>
> print STDOUT "child_file_out\n";
> print STDERR "child_file_err\n";
>
> system("xcopy");
>
> close(STDERR);
> close(STDOUT);
>
> open(STDOUT, ">&SAVEOUT");
> open(STDERR, ">&SAVEERR");
>
> print STDOUT "child_screen_out\n";
> print STDERR "child_screen_err\n";
> }
This test seems to function as expected:
my $ERR_FILE = "c:\\tmp\\err.txt";
my $OUT_FILE = "c:\\tmp\\out.txt";
unlink $ERR_FILE;
unlink $OUT_FILE;
foreach (1 .. 3) {
print STDOUT "parentscreenout ($_)\n"; # prints to screen
print STDERR "parentscreenerr ($_)\n"; # prints to screen
my $pid1 = fork ();
if ($pid1 == 0) {
run ($_);
exit 0;
}
sleep 5;
print STDOUT "parentscreenout2 ($_)\n"; # prints to screen
print STDERR "parentscreenerr2 ($_)\n"; # prints to screen
}
exit;
sub run {
local $_ = shift;
print STDOUT "childscreenout ($_)\n"; # prints to screen
print STDERR "childscreenerr ($_)\n"; # prints to screen
open SAVEOUT, ">&STDOUT";
open SAVEERR, ">&STDERR";
open STDERR, ">>${ERR_FILE}";
open STDOUT, ">>${OUT_FILE}";
print STDOUT "child_file_out ($_)\n"; # prints to file
print STDERR "child_file_err ($_)\n"; # prints to file
close STDERR;
close STDOUT;
open STDOUT, ">&SAVEOUT";
open STDERR, ">&SAVEERR";
print STDOUT "childscreenout2 ($_)\n"; # prints to screen
print STDERR "childscreenerr2 ($_)\n"; # prints to screen
}
__END__
--
,-/- __ _ _ $Bill Luebkert ICQ=162126130
(_/ / ) // // DBE Collectibles Mailto:[EMAIL PROTECTED]
/ ) /--< o // // http://dbecoll.tripod.com/ (Free site for Perl)
-/-' /___/_<_</_</_ Castle of Medieval Myth & Magic http://www.todbe.com/
_______________________________________________
ActivePerl mailing list
[EMAIL PROTECTED]
To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
