Backticks and exec within a CGI

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

I'm trying to write a CGI that's a simple wrapper script around ASPSeek. I want to tinker with the environment variables, and maybe filter the output, though this might not be necessary. What I'm trying at the moment:

#!/usr/bin/perl
print "Content-type: text/html\n\n";
print `/path/to/aspseek/s.cgi`;
[download]

This works fine from the command line run as the user Apache runs as (nobody), and s.cgi runs fine a standalone CGI, but nothing gets printed when I run it within the wrapper script; the backticks return an empty string. $? is 0. What I'm wondering is how "the outside" looks different to a CGI run in backticks by a perl CGI. Incidentally, exec doesn't work either.

cheers
ViceRaid

Comment on Backticks and exec within a CGI Download Code

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Re: Backticks and exec within a CGI by Abigail-II (Bishop) on Feb 20, 2004 at 14:48 UTC
Note that the environment is different when running as a CGI program, and running from the command line. This includes, but is not limited to, (E)UID, (E)GID, environment variables, and the root file system. $? suggests that /path/to/aspseek/s.cgi was run, and was run successfully. It just might have decided not to output anything. Abigail	[reply]
Re: Backticks and exec within a CGI by skx (Parson) on Feb 20, 2004 at 17:30 UTC
Do you see anything in your servers error logs? It might be the case, for example, that the `s.cgi` script you are calling won't like getting called in this manner - expecting to be able to use PATH_INFO or some other variable which you've not massaged correctly. Steve --- steve.org.uk	[reply]
Re: Re: Backticks and exec within a CGI by ViceRaid (Chaplain) on Feb 20, 2004 at 19:22 UTC
Ah, yes, that's it. It works when I massage SCRIPT_URL so it reflects the original CGI, it works. It turns out that the application uses this to find a template file, but doesn't complain or fall back to a default if this file's missing, it just prints nothing and returns a success. cheers ViceRaid	[reply]