systab/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Overview

systab is a single-file Bash script that provides a cron/at/batch-like interface for systemd user timers. It creates, manages, and cleans up systemd .service and .timer unit files in ~/.config/systemd/user/. Managed units are tagged with a # SYSTAB_MANAGED marker comment and a # SYSTAB_ID=<hex> short ID for human-friendly identification.

Running

./systab [OPTIONS]

No build step. The script requires bash, systemctl, and optionally notify-send (for -i) and mail (for -m).

Architecture

The script has two modes controlled by CLI flags:

• Job creation (-t <time> [-c <cmd> | -f <script> | stdin]): Generates a systemd .service + .timer pair with a 6-char hex short ID, reloads the daemon, and enables/starts the timer. Time specs are parsed via date -d or passed through as systemd OnCalendar values. One-time jobs get Persistent=false and RemainAfterElapse=no (auto-unload after firing).

• Management (-E, -L, -S, -C — mutually exclusive):

  • -E: Opens $EDITOR with a tab-separated crontab (ID SCHEDULE COMMAND). On save, diffs against the original to apply creates (ID=new), deletes (removed lines), and updates (changed schedule/command). Legacy jobs without IDs get one auto-assigned.
  • -L [filter]: Query journalctl logs for managed jobs.
  • -S: Show timer status via systemctl, including short IDs.
  • -C: Interactively clean up elapsed one-time timers (removes unit files from disk).

Key functions: parse_time (time spec → OnCalendar), create_job (generates unit files), edit_jobs (crontab-style edit with diff-and-apply), get_managed_services/get_managed_timers (find tagged units), ensure_job_id (auto-assign IDs to legacy jobs), clean_jobs (remove elapsed one-time timers).

Testing

There are no automated tests. Test manually with systemd user timers:

./systab -t "in 1 minute" -c "echo test"
./systab -S
./systab -C

Notes

• ShellCheck can be used for linting: shellcheck systab.