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cronjobs

Automation with cronjobs

You can set scheduled tasks with cronjobs, to run any function at any given time.

Most used ones are:

  • Automatically check for updates (update command)
  • Automatically check for server crash and restart if needed (monitor command)
  • Automatically keep LinuxGSM up to date (update-functions command)
  • Automatically restart the server at a given time (restart command)
  • Automatically update and restart the server (force-update command)

Command

To access and edit your cronjobs, input
crontab -e

Cronjob as user or root

When setting up cronjobs there is a choice of running them as a user or as root. If an admin runs several servers and wants to centrally manage cronjobs then using the root crontab is a good idea. If an admin wants them separated, the user crontab is best.

Crontab Syntax

User cronjobs

* * * * * [/path/to/script] [command] > /dev/null 2>&1

Root cronjobs

* * * * * su - username -c '[/path/to/script] [command]' > /dev/null 2>&1

Note: >/dev/null 2>&1 is required to mute any output.

Temporal values

* can be considered as "bypass" values by some, but means "whatever the value is, do it".
You can replace them by numerical values standing for
minutes - hours (24h format) - days - month - day of the week (Sunday =0 to Saturday =6)

A numerical x value would mean "when it is this value".
While a */x means every x time.

Of course, you can combine those rules smartly to achieve what you want.

Every "x" time

In order to run a command, such as "monitor" every "x" time, there is a simple solution.
Replace * by */x, "x" being the desired numerical value.
Think about defining smaller amounts of time to a fixed value when using this. For example, if you wish to have an "every two hours" cronjob, you'll need to set a fixed value for minutes.

Temporal values examples

Every single minute
* * * * *

Every 30 minutes
*/30 * * * *

Every hour
0 * * * *

Every two hours
0 */2 * * *

Every two hours when it's 30 minutes on the clock 30 */2 * * *

Every day at 5:10 PM
10 17 * * *

Every Wednesday at 1 AM
0 1 * * * 3

Every five days at 1 AM
0 1 */5 * *

Cronjob generator

If you have any doubt about a particular syntax, you can use this generator : http://crontab-generator.org/

LinuxGSM Cronjobs examples

Daily cronjobs

Replace the username and gameserver according to your case

Here is an example of a user based cronjob for daily restart at 5am :

0 5 * * *  /home/username/gameserver restart > /dev/null 2>&1

Here is an example of a root based cronjob for daily restart at 5am :

0 5 * * *  su - username -c '/home/username/gameserver restart' > /dev/null 2>&1

Every x time cronjobs

Replace the username and gameserver according to your case

Here is an example of a user based cronjob to monitor your server every 3 minutes :

*/3 * * * *  /home/username/gameserver monitor > /dev/null 2>&1

Here is an example of a root based cronjob to monitor your server every 3 minutes :

*/3 * * * *  su - username -c '/home/username/gameserver monitor' > /dev/null 2>&1

Full examples

Complete setup for one gameserver

Replace the username and gameserver according to your case

####CRONJOBS####

### Game Name
#Server Name
*/5 * * * * su - username -c '/home/username/gameserver monitor' > /dev/null 2>&1
*/30 * * * * su - username -c '/home/username/gameserver update' > /dev/null 2>&1
30 6 * * *  su - username -c '/home/username/gameserver force-update' > /dev/null 2>&1
0 0 * * 0 su - username -c '/home/username/gameserver update-functions' > /dev/null 2>&1
  • Will monitor your server every 5 minutes
  • Will check for an update every 30 minutes, update and restart only if an update is detected.
  • Will restart and check for an update every day at 6:30 AM
  • Will update your LinuxGSM functions every Sunday at midnight.

Real life multiple servers example

####CRONJOBS####

###TeamSpeak###
# TS3Community
*/1 * * * *  su - ts3server -c '/home/ts3server/ts3server monitor' > /dev/null 2>&1
30 6 * * *  su - ts3server -c '/home/ts3server/ts3server update' > /dev/null 2>&1
0 0 * * 0 su - ts3server -c '/home/ts3server/ts3server uf' > /dev/null 2>&1

###GMOD###
# ProBuild
*/2 * * * *  su - gmodprobuild -c '/home/gmodprobuild/gmodserver monitor' > /dev/null 2>&1
0 5 * * *  su - gmodprobuild -c '/home/gmodprobuild/gmodserver fu' > /dev/null 2>&1
0 0 * * 0 su - gmodprobuild -c '/home/gmodprobuild/gmodserver uf' > /dev/null 2>&1
# Prophunt
*/2 * * * *  su - gmodprophunt -c '/home/gmodprophunt/gmodserver monitor' > /dev/null 2>&1
0 5 * * *  su - gmodprophunt -c '/home/gmodprophunt/gmodserver fu' > /dev/null 2>&1
0 0 * * 0 su - gmodprophunt -c '/home/gmodprophunt/gmodserver uf' > /dev/null 2>&1


###CSS###
# GunGame
*/2 * * * *  su - cssgungame -c '/home/cssgungame/cssserver monitor' > /dev/null 2>&1
30 5 * * *  su - cssgungame -c '/home/cssgungame/cssserver fu' > /dev/null 2>&1
0 0 * * 0 su - cssgungame -c '/home/cssgungame/cssserver uf' > /dev/null 2>&1

###RUST###
# Modded
## Server stopped
#*/5 * * * * su - rustmodded -c '/home/rustmodded/rustserver monitor' > /dev/null 2>&1
#30 6 * * *  su - rustmodded -c '/home/rustmodded/zip-updater/zip-updater' > /dev/null 2>&1
#0 0 * * 0 su - rustmodded -c '/home/rustmodded/rustserver uf' > /dev/null 2>&1

#Vanilla
*/5 * * * * su - rustvanilla -c '/home/rustvanilla/rustserver monitor' > /dev/null 2>&1
*/30 * * * * su - rustvanilla -c '/home/rustvanilla/rustserver update' > /dev/null 2>&1
30 6 * * *  su - rustvanilla -c '/home/rustvanilla/rustserver fu' > /dev/null 2>&1
0 0 * * 0 su - rustvanilla -c '/home/rustvanilla/rustserver uf' > /dev/null 2>&1

###ARK###
*/30 * * * * su - arkserver -c '/home/arkserver/arkserver monitor' > /dev/null 2>&1
0 6 * * 5  su - arkserver -c '/home/arkserver/arkserver fu' > /dev/null 2>&1
0 */1 * * * su - arkserver -c '/home/arkserver/arkserver update' > /dev/null 2>&1
0 0 * * 0 su - arkserver -c '/home/arkserver/arkserver uf' > /dev/null 2>&1

Protips

  • Note the "fu" (for "force-update") which will check for an update and restart your server even though there is no update. It is a good alternative if you don't wish to use the updateonstart functionality.
  • It's a good practice to comment cronjob lines of a server that you momentarily want to shutdown in order to add back cronjobs more easily afterwards.
  • Some servers crash more often, so it's a good idea to monitor them more frequently. However, you shouldn't monitor faster than once every 2 minutes, otherwise the monitor function might behave inconsistently, and your server might bootloop.
  • You can also sparingly run "every x time" update checks, for games getting updated a lot.
  • As you can see for the commented Rust server, you can also run your own custom scripts if the task is more complicated than just an LinuxGSM command.
  • Ultimately, it's wise to add an "uf" cronjob (for "update-functions") in order to keep LinuxGSM up to date.