scrontab: Manage Slurm Crontab Files

Introduction

scrontab is a focused tool for managing Slurm job scheduler crontab entries. If you’re used to crontab on Linux, scrontab adds Slurm-specific semantics while keeping the familiar edit/list/remove workflow. This quick guide shows practical usage, pitfalls, and concrete examples to get you started.

Quick start: common commands

  • Install a new crontab from a file:
scrontab /path/to/file
  • Edit the crontab of the current user:
scrontab -e
  • Edit the crontab of a specific user:
scrontab --user=username -e
  • Remove the current user’s crontab:
scrontab -r
  • Print the current user’s crontab to stdout:
scrontab -l

Practical examples

  1. Install from a prepared file
  • You might have a file with Slurm-specific directives. Ensure the file has valid syntax for a crontab-like entry. Then:
scrontab /home/me/slurm_crontab.txt
  1. Edit the current user’s crontab
  • Quick edits without leaving the shell:
scrontab -e
  1. Edit another user’s crontab (requires root or appropriate privileges)
  • If you’re an administrator, you can adjust another user’s schedule:
scrontab --user=alice -e
  1. Remove a user’s crontab
  • Be careful: this is destructive and cannot be undone from scrontab alone. Consider backing up first.
scrontab -r
  1. List a user’s crontab without editing
  • Quick check of what’s scheduled:
scrontab -l

Common pitfalls and how to avoid them

  • Forgetting to back up before -r
    • Always create a backup before deleting a crontab, e.g. by exporting to a file:
scrontab -l > ~/crontab-backup-$(date +%F).txt

  • Running as the wrong user

    • Commands like —user require proper privileges. Running as a non-root user won’t affect other users.
    • Verify current user with whoami and confirm privileges before editing another user’s crontab.

  • File format mismatches

    • The scrontab file should follow the expected format. A malformed line can cause scrontab to fail. Validate by testing small changes first.

  • Not updating the cache

    • If tldr indicates cache issues or you’re in an environment with stale cache, run tldr —update to refresh examples and docs.

Best practices

  • Backup before making changes: always export before editing or removing.
  • Use explicit —user when operating on others, and verify permissions.
  • Keep comments in your crontab file to document why a rule exists.
  • Validate with -l after changes to confirm the expected schedule appears.

Troubleshooting quick tips

  • scrontab -l shows nothing or errors

    • Check permissions and that you’re targeting the correct user.
    • Ensure the Slurm environment is installed and configured on the host.

  • Changes don’t seem to apply

    • Some systems require a Slurm daemons restart to pick up changes, though scrontab typically updates the scheduler configuration directly. Check service status if in doubt.

Conclusion

scrontab provides a straightforward path to manage Slurm crontab entries, mirroring the familiar crontab workflow with Slurm-aware context. Start with small edits, back up often, and always confirm the resulting schedule with scrontab -l.

See Also