How can I find if a certain part of Linux is installed?
 

As the above states, I am having trouble finding if glibc, opengl, ect. are installed on my computer. How would I go about finding if they are installed or not? And why does every time I go to install something, some dependancy error pop up?

If your looking for packages installed on a default install with Slackware, you can easily do a:

ls -al /var/log/packages | grep <package-name>

If they were supposedly not installed using the tgz packages that Slackware uses like source or RPM's, you won't find them in this directory.

Regards.

Thanks, it is installed. Now, to figure out how to get GLHeretic and Doom to work, heheh. Another five minutes, another google search.