For anyone that might find this helpful if you are thinking of hosting games with either the old Source[en.wikipedia.org] engine or the ancient GoldSrc[en.wikipedia.org] engine on a headless Linux server, I published my scripts and built a Steam Community "Guide" for their setup and usage ...

Weasel's Dedicated-Server Management Scripts (for Linux)
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3192671225

The sample scripts provided allow for easily completing many tasks associated with hosting dedicated game-servers. This includes things such as:

• Installing the game-servers in a consistent manner.
  
• Running the game-servers interactively at the console for testing / troubleshooting.
  
• Starting the game-servers as disconnected / back-ground processes - so that they can run unattended.
  
• Stopping the disconnected / back-ground processes of the game-servers.
  
• Manually updating the game-servers if needed.
  
• Checking for updates available for the game-servers, and conditionally updating the game-servers, restarting them only if an update is needed.
  
• Making backups of the game-servers.
  
• Generating lists of "stock" content to exclude from backups.