Downloading a Dedicated Server
Dedicated servers are now downloaded using SteamCMD. This is a command line version of Steam.
You can download it from this page.
The first time you run it it will update and you will be left at a STEAM> console. You will want to log in. You can log into an anonymous account by typing:
Installing & Updating Garry's Mod Dedicated Server
If you want to specify a download folder then before you update enter this command:
This is known to cause problems when updating your server to a newer version. If your server fails to update, try not using the force_install_dir feature, or try reinstalling your server into another folder
You can then install or update the Garry's Mod Dedicated Server by using the command: app_update 4020
It will slowly download or update.
If you wish to verify your server, enter this instead of the above: app_update 4020 -validate
Once it's done you can type quit at the console to exit or just close the SteamCMD window.
You probably don't want to do that every time you want to install/update a server. Don't worry - it supports command lines too.
steamcmd.exe +login anonymous +app_update 4020 validate +quit
Main article: Linux Dedicated Server Hosting
Install SteamCMD as per the recommendations from the Valve Developer Wiki.
Then install the GMod dedicated server in a similar manner to Windows:
steamcmd +login anonymous +force_install_dir ../gmodds +app_update 4020 validate +quit
The server is now available in ~/gmodds/.
cd ~/gmodds/ ./srcds_run -game garrysmod +maxplayers 32 +map gm_construct
If you get the error message ./steamcmd.sh: line 29: /home/$USER/Steam/linux32/steamcmd: No such file or directory You are most likely running 64 a bit system and missing 32 bit libraries.
If the output of this command is x86_64, you are running a 64 bit system and need 32 bit libraries. uname -m See this article on the valve wiki. 32-bit libraries on 64-bit Linux systems
macOS dedicated servers are no longer shipped.
The Experimental Branches
To update your server to the development branch, you'll have to launch your SteamCMD and enter these commands manually:
login anonymous app_update 4020 -beta dev validate quit
For the pre-release branch: login anonymous app_update 4020 -beta prerelease validate quit
To revert back to stable branch: login anonymous app_update 4020 -beta NONE validate quit
The development branch is updated regularly.