Programming Tips - How can I let a user on a webpage exec a command as another user?

Date: 2012apr20 OS: Linux Q. How can I let a user on a webpage exec a command as another user? (The webserver runs as user "apache" but I need to do a command as a different user) A. There are several different ways to do this. Here's one that is pretty nice. Let's say you what your users to be able to run command /usr/lib/mailman/bin/inject as user mailman via a php page you made. Add this to your /etc/sudoers file:
Defaults:apache !requiretty %apache ALL=(mailman) NOPASSWD: /usr/lib/mailman/bin/inject
Then your php script can do:
system("sudo -u mailman /usr/lib/mailman/bin/inject ...");
As you can see, we are using the powerful sudo command to make this happen.