scrontab / ITS Documentation

Overview

The scrontab command in Slurm allows users to schedule recurring batch jobs, similar to the traditional cron utility. This tool enables the automation of tasks at specified intervals, leveraging Slurm’s workload management capabilities.

Notice: ARC does not monitor the state of scrontab jobs. Users are responsible for managing and ensuring the proper execution of their scheduled tasks.

Creating and using scrontab

Edit your crontab (this will use vim by default)

scrontab -e

When you save your script, Slurm will automatically schedule it to run at the specified interval. By default, it uses the text editor vim. To change it, update the environmental variable EDITOR to your preferred editor.

When setting times for tasks, it's often easiest to use standard cron time intervals like @hourly or @daily to indicate when you want your job to run. For example:

@daily /path/to/your/script.sh

If you need a specific time, you can specify it using the standard cron format:

* * * * * command

The five asterisks represent the following time fields:

1. Minute: (0-59)

2. Hour: (0-23)

3. Day of Month: (1-31)

4. Month: (1-12 or names)

5. Day of Week: (0-7, where both 0 and 7 represent Sunday, or names)

For example, to run a script every day at 3:30 AM:

30 3 * * * /path/to/your/script.sh

Example scrontab script

This scrontab script specifies the account, partition, and duration the job is expected to run. It will be eligible to run at midnight every day and will append the output of each job to a file named output-XXXXX.out (where XXXXX is the Slurm job ID).

#SCRON -A <account>
#SCRON -p standard
#SCRON -t 00:30:00
#SCRON -J sc_test
#SCRON -o output-%j.out
#SCRON --open-mode=append
@daily $HOME/scripts/your_script.sh

Monitoring and Managing `scrontab` Jobs

To view your current `scrontab` entries

scrontab -l

To remove your `scrontab` entries (currently running jobs will continue to run)

scrontab -r

To monitor your scheduled jobs, use the squeue command (list all jobs in the queue including those scheduled via scrontab)

squeue -u $USER

For more detailed information on scrontab, refer to the official Slurm documentation: https://slurm.schedmd.com/scrontab.html

Note: As previously mentioned, ARC does not monitor the state of scrontab jobs. It is the user’s responsibility to manage and verify the execution of their scheduled tasks.