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

I'm trying to have a CGI script ("") call another CGI script ("b.cgi"), using system(). ("b.cgi" is used elsewhere; I just want to grab its (json) output and do things with it (using Capture::Tiny).

This works fine from the command line, but from the browser, "b.cgi" doesn't get the parameters that "" sends... or rather, the parms end up in @ARGV rather than $query->param.

Here's a minimal example. In this example, I'm not trying to process b.cgi's output in I just want to show that b.cgi is not getting the parameters in $query->param.

#!/usr/bin/perl use strict; use warnings; my @args = ("animal=duck", "vegetable=carrot"); system("/usr/bin/perl", "/tmp/b.cgi", @args);

and b.cgi:

#!/usr/bin/perl use warnings; use strict; use CGI; my $query = new CGI; print "Content-type: text/plain\n\n"; print "b.cgi query dump:\n"; print $query->Dump . "\n"; print "b.cgi argv dump:\n"; print join(',', @ARGV); print "\n";

Output when is invoked from the command line:

Content-type: text/plain b.cgi query dump: <ul> <li><strong>animal</strong></li> <ul> <li>duck</li> </ul> <li><strong>vegetable</strong></li> <ul> <li>carrot</li> </ul> </ul> b.cgi argv dump: animal=duck,vegetable=carrot

Output when is invoked through the browser:

b.cgi query dump: <ul></ul> b.cgi argv dump: animal=duck,vegetable=carrot

Is there some difference between a command-line invocation and a system() invocation?

I'm clearly misunderstanding something here... Any help you could give would be... well... helpful!

update: spelling

Replies are listed 'Best First'.
Re: Invoking a cgi script from another cgi script using system()
by Anonymous Monk on Dec 31, 2014 at 22:50 UTC

    you have to read the source for the module , someone may have edited it to enable/disable @ARGV processing

    Although, if your cgi program consisted of

    use MyApp; MyApp->runcgi;

    then you wouldn't have to use system to call your cgi program, you could use MyApp .... regular perl programming

      Ah, yes. That's better :-)

      (In the real project, I'm going to pull the guts out of "b.cgi" into a new "", and have both and b.cgi use to do the heavy lifting, without needing to mess about with having capturing output from b.cgi)

      Thanks for the tip on, too. $DEBUG was actually set to 1 (meaning that this *should* have worked...) I still don't know why it didn't work, but I learned something new today, and that's always a win.


        You could also write like this because webservers won't put stuff into @ARGV
        my $query = @ARGV ? CGI->new({ @ARGV }) : CGI->new;

        Invoke as

        system $^X, 'foo.cgi', qw/ key value key value /;
Re: Invoking a cgi script from another cgi script using system()
by bibliophile (Prior) on Dec 31, 2014 at 21:36 UTC

    I should note that invoking b.cgi from the browser ("/cgi-bin/b.cgi?animal=dog&vegetable=radish") works, giving:

    b.cgi query dump: <ul> <li><strong>animal</strong></li> <ul> <li>dog</li> </ul> <li><strong>vegetable</strong></li> <ul> <li>radish</li> </ul> </ul> b.cgi argv dump: