`(bacticks) returns "Bad File Descriptor" error with Apache



I wanted to run a command line program from Ruby. I used `(backticks) to
do this. It was successful if I run the program using Webrick but if I
run it using Apache 2.2.8, a “Bad File Descriptor” error is returned.

I needed to run svn list command to get the names of the files in a
target repository located in another machine. Using `(backticks) to run
the command gives me the output that i need.

This is my code:
svn list #{path}
#path is the location of the SVN repository in another machine

Does anybody have any idea why `(backticks) return this kind of error in

I have already used some of the suggested ways in this site:

Please help.
Thank you very much.