Does any of this (truncated) look helpful? relevant? 
C:\>perldoc -q stderr
Found in C:\Perl\lib\pods\perlfaq8.pod
  How can I capture STDERR from an external command?
    There are three basic ways of running external commands:

            system $cmd;            # using system()
            $output = `$cmd`;               # using backticks (``)
            open (PIPE, "cmd |");   # using open()

    With "system()", both STDOUT and STDERR will go the same place as 
+the
    script's STDOUT and STDERR, unless the "system()" command redirect
+s
    them. Backticks and "open()" read only the STDOUT of your command.

    You can also use the "open3()" function from "IPC::Open3". Benjami
+n
    Goldberg provides some sample code:

    To capture a program's STDOUT, but discard its STDERR:

            use IPC::Open3;
            use File::Spec;
            use Symbol qw(gensym);
            open(NULL, ">", File::Spec->devnull);
            my $pid = open3(gensym, \*PH, ">&NULL", "cmd");
            while( <PH> ) { }
            waitpid($pid, 0);

    To capture a program's STDERR, but discard its STDOUT:

            use IPC::Open3;
            use File::Spec;
            use Symbol qw(gensym);
            open(NULL, ">", File::Spec->devnull);
            my $pid = open3(gensym, ">&NULL", \*PH, "cmd");
            while( <PH> ) { }

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In reply to Re: How to capture child process output and divert to log4perl by ww
in thread How to capture child process output and divert to log4perl by chrestomanci

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