Why can't I find System.Text.RegularExpressions when using Mono in Linux?

Question

I'm attempting to use Mono and Monodevelop (the IDE) to code a C# project in Ubuntu.

Everything is working apart from the fact that the System.Text.RegularExpressions (Package?) is not found. The only relevant thing I have found on the interwebs is here

There appears to be a solution of sorts posted, but I don't understand. Please help :)

Answer 1

In MonoDevelop, right click on References and add a reference to the System assembly.

You could use gmcs -r System *.cs to compile from command line.

Answer 2

Same here in VS2010. Just add a reference to System if Assembly is missing.