Scheduled tasks (cron): Difference between revisions

Latest revision as of 12:58, 18 June 2026

Recurring, scheduled tasks on Anunna should be run through the scheduler with scrontab, SLURM's built-in cron. scrontab uses the familiar crontab syntax, but runs each scheduled task as a SLURM job on a compute node — so your recurring work gets proper resources and does not load the shared login nodes.

 ⚠️ Warning: Do not use a plain login-node crontab for recurring work. Anything scheduled with crontab runs on the login node, which is a shared access point not meant for computation, and the crontab is wiped when the login node reboots. Use scrontab instead.

Using scrontab

Edit your scrontab with:

scrontab -e

Each entry has two parts: one or more #SCRON lines that set the SLURM options for the job (partition, time limit, resources, job name, …), followed by a normal crontab time specification and the command to run.

#SCRON --partition=main
#SCRON --time=00:10:00
#SCRON --job-name=daily-download
0 2 * * * /home/<group>/<username>/scripts/download.sh

This runs download.sh as a SLURM job every day at 02:00. List your current entries with:

scrontab -l

The crontab time format (the 0 2 * * * part) is described in the crontab manual page:

man 5 crontab

@@ Line 1: / Line 1: @@
+Recurring, scheduled tasks on Anunna should be run through the scheduler with '''scrontab''', SLURM's built-in cron. scrontab uses the familiar crontab syntax, but runs each scheduled task as a SLURM job on a compute node — so your recurring work gets proper resources and does not load the shared login nodes.
-== Using crontab ==
+{{Warning|Do not use a plain login-node <code>crontab</code> for recurring work. Anything scheduled with <code>crontab</code> runs on the login node, which is a shared access point not meant for computation, and the crontab is wiped when the login node reboots. Use <code>scrontab</code> instead.}}
-With crontab you can run jobs on a fixed time schedule.
+== Using scrontab ==
-This means that you can e.g. download some data every day.
-To start an edit with '''crontab -l''' , the info on that file can be found by using '''man 5 crontab'''.
+Edit your scrontab with:
-Be aware of the following :
+<syntaxhighlight lang="bash">
+scrontab -e
+</syntaxhighlight>
-The scripts will run on the login node, so do not use a lot of resources
+Each entry has two parts: one or more <code>#SCRON</code> lines that set the SLURM options for the job (partition, time limit, resources, job name, …), followed by a normal crontab time specification and the command to run.
-The crontab entry will be wiped upon reboot, so if you want to make sure that it is there, it wise to set that up.
+<syntaxhighlight lang="bash">
+#SCRON --partition=main
+#SCRON --time=00:10:00
+#SCRON --job-name=daily-download
+2 * * * /home/<group>/<username>/scripts/download.sh
+</syntaxhighlight>
+This runs <code>download.sh</code> as a SLURM job every day at 02:00. List your current entries with:
+<syntaxhighlight lang="bash">
+scrontab -l
+</syntaxhighlight>
+The crontab time format (the <code>0 2 * * *</code> part) is described in the crontab manual page:
+<syntaxhighlight lang="bash">
+man 5 crontab
+</syntaxhighlight>
+== See also ==
+* [[Batch Jobs]]
+* [[Scheduler Overview (Slurm)]]

Scheduled tasks (cron): Difference between revisions

Latest revision as of 12:58, 18 June 2026

Using scrontab

See also

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