Some CGI "tips"

Bash wrapper script

With Apache (2.2) you could get an generic "Internal Server Error" error message in case the cgi sends the wrong headers. There is probably a setting for this in Apache as well, but I always create a bash wrapper script. For example someapp.cgi:

#!/bin/bash
printf "Content-type: text/html\n\n"
/path/to/actual_appl

This immediately makes the output visible and you can comment the printf statement once fixed. This trick only makes sense if you don't have quick access to a debugger or a core dump.

Running application in chroot

There are plugins for apache AFAIK for running cgi applications in a chroot. I didn't experiment with these, as I simply use my (probably lame) bash wrapper here as well:

#!/bin/bash
sudo -E /usr/bin/chroot /usr/local/src/some_jail /usr/bin/some_appl 2>&1

The -E flag means "preserve environment". To allow this you have to configure sudoers properly (visudo). Something like this:

wwwrun ALL=(ALL) SETENV: ALL, NOPASSWD : /usr/bin/chroot