One of the biggest annoyances with CS:GO compared to the other counter strikes is the inability to use the -autoupdate command. There is a quick workaround, though, that just requires the creation of one text file.
To your server's start command line, you need to add two commands:
-steam_dir /path/to/steam/dir -steamcmd_script restart.txt
For example, mine looks like this:
-steam_dir /home/gamer/go/steamcmd -steamcmd_script deathmatch.txt
Within your steamcmd directory, you need to create a txt file that contains four lines:
For example, my deathmatch.txt looks like this: