Perl, Pipes, and PHP's POpen, oh my!

[gwfran]

I'm having a heck of a time trying to translate php's popen command to something that I can use in Perl (in both Win32 and Unix environs).


function filterThroughCmd($input, $commandLine) {
$pipe = popen("echo \"$input\"|$commandLine" , 'r');
if (!$pipe) {
print "pipe failed.";
return "";
}
$output = '';
while(!feof($pipe)) {
$output .= fread($pipe, 1024);
}
pclose($pipe);
return $output;
}


Where $input is a significant chunk of text (with newlines) being pushed into the command "matchmol.exe -".

It's a challenge... :thumbsup:

[ralph l mayo]

I haven't used this, but it seems to work:


sub filterThroughCmd
{
my ($input, $cmd) = @_;
open FILTER, "|$cmd" or die $!;
print FILTER $input;
my @resp = <FILTER>;
close FILTER;
return wantarray? @resp : join @resp, "\n";
}

print filterThroughCmd("just\na\ntest", 'wc -l');

[gwfran]

Thanks Ralph - I'm going to try it right now!!!!!! :thumbsup:

[gwfran]

Holy cow - the problem was that I was getting CRCRLF's from Perl!!!
A simple regex cured that.

As I step through the code, the open FILTER and print FILTER work great. The results of these two lines are immediately printed to the screen. For some reason @resp = <FILTER> is not catching the results and storing them.

Any ideas?

[FishMonger]

Please show us the code that you're testing.

[FishMonger]

Have you tried using backticks to retrieve the output of your external program?

@resp = `echo $input | $commandLine`;

[FishMonger]

If you want to use the more verbose approach, this should work.

sub filterThroughCmd
{
my ($input, $cmd) = @_;
open FILTER, "| echo $input | $cmd" or die $!;
my @resp = <FILTER>;
close FILTER;
return @resp;
}

[gwfran]

Thanks Fishmonger.

The code I'm testing is what Ralph provided.

I've tried the backtick and echo-ing of the input and I always get "bad file descriptor" errors.

I'd post the file I'm trying to pipe into matchmol.exe, but it's huge (12 Megs).

I'll probably just shunt the results to a file and then open the file. The result file is small enough - I was mostly worried about having to save the 12 Meg file out to a file, run matchmol.exe, and then pull a file back. No biggie. Ralph's code and my finding the CRCRLF gets me uber close to the result.

Thanks for your help!