I'm trying to stream a file from a remote website to a local command and am running into some problems when trying to detect errors. The code looks something like this: use IPC::Open3; my @cmd = ('wget','-O','-','http://10.10.1.72/index.php');#any website will do here my ($wget_pid,$wget_in,$wget_out,$wget_err); if (!($wget_pid = open3($wget_in,$wget_out,$wget_err,@cmd))){ print STDERR "failed to run open3\n"; exit(1) } close($wget_in); my @wget_outs = <$wget_out>; my @wget_errs = <$wget_err>; print STDERR "wget stderr: ".join('',@wget_errs); #page and errors outputted on the next line, seems wrong print STDERR "wget stdout: ".join('',@wget_outs); #clean up after this, not shown is running the filtering command, closing and waitpid'ing When I run that wget command directly from the command-line and redirect stderr to a file, something sane happens - the stdout will be the downloaded page, the stderr will contain the info about opening the given page. wget -O - http://10.10.1.72/index.php 2> stderr_test_file When I run wget via open3, I'm getting both the page and the info mixed together in stdout. What I expect is the loaded page in one stream and STDERR from wget in another. I can see I've simplified the code to the point where it's not clear why I want to use open3, but the general plan is that I wanted to stream stdout to another filtering program as I received it, and then at the end I was going to read the stderr from both wget and the filtering program to determine what, if anything went wrong. Other important things: I was trying to avoid writing the wget'd data to a file, then filtering that file to another file, then reading the output. It's key that I be able to see what went wrong, not just reading $? 8 (i.e. I have to tell the user, hey, that IP address is wrong, or isn't the right kind of website, or whatever). Finally, I'm choosing system/open3/exec over other perl-isms (i.e. backticks) because some of the input is provided by untrustworthy users.