You are looking for a guide on how to use LanGuard to deploy updates to your Linux machines.
You can run interactive scans or schedule them, and patch Linux machines/servers directly from the LanGuard console, as LanGuard agents can be deployed only on Windows machines. LanGuard communicates with the Linux machine's Package Manager which does the scanning and patching.
If a Linux computer is not connected to the Internet, GFI LanGuard won't be able to patch it. There is no workaround.
Please, check all the requirements for GFI LanGuard to scan and patch Linux Operating Systems.