Ok, so you may get the error stating:
Failed to open dedicated_srv.so ( /lib/i386-linux-gnu/libm.so.6: version `GLIBC_2.15' not found ( required by bin/dedicated_srv.so ) )
Well, here is how to fix it!
dpkg -x libc6_2.15-0ubuntu10.6_i386.deb tmp/
cp * /your-garrysmod-directory/bin/
Why am I writing this?: Because the official link for libc5_2.15 (10.6) is now not available, but is still needed for many gmod servers!
Tell me if this helped…