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. Unit filenames use a 6-char hex ID (e.g., systab_a1b2c3.timer) which doubles as the human-facing job identifier.

Running

./systab [OPTIONS]

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

Architecture

The script has two modes controlled by CLI flags:

• Job creation (-t <time> [-n <name>] [-c <cmd> | -f <script> | stdin] or -s [-n <name>] [-c <cmd> | -f <script> | stdin]): Generates a systemd unit pair (or single unit for services) with a 6-char hex short ID, reloads the daemon, and enables/starts the unit. An optional -n <name> assigns a human-readable name that can be used interchangeably with hex IDs in all operations.

  • Timer jobs (-t): Creates a .service + .timer pair. Time specs are parsed via parseTime which handles natural language (every 5 minutes), date -d relative/absolute times, and raw systemd OnCalendar values. One-time jobs get Persistent=false and RemainAfterElapse=no (auto-unload after firing). Notifications (-i desktop, -m email, -o include output) use ExecStopPost so they fire on both success and failure with status-aware icons/messages. The -o [N] flag fetches the last N lines of journal output (default 10). Notification flags are persisted in the service file as a # SYSTAB_FLAGS= comment.
  • Service jobs (-s): Creates a single .service file with Type=simple, Restart=on-failure, and WantedBy=default.target. No .timer file is created. A daemon-reload runs before enable/start so systemd registers the unit first. Service jobs are tagged with # SYSTAB_TYPE=service in the service file. Mutually exclusive with -t, -i, -m, -o.

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

  • -D <id|name> / -E <id|name>: Disable (stop+disable) or enable (enable+start) a job's timer. Accepts hex ID or name.
  • -e: Opens $EDITOR with a pipe-separated crontab (ID[:FLAGS] | SCHEDULE | COMMAND). Flags are appended to the ID with : (s = service, i = desktop, e=addr = email, o = output 10 lines, o=N = output N lines, n=name = job name, comma-separated). Service jobs appear with service as the schedule column. On save, diffs against the original to apply creates (ID=new), deletes (removed lines), updates (changed schedule/command/flags), and disable/enable (comment/uncomment lines). The service schedule keyword skips parseTime validation and routes to _writeUnitFiles with job_type=service.
  • -L [id|name] [filter]: Query journalctl logs for managed jobs (both unit messages and command output). Optional job ID or name to filter to a single job.
  • -S [id|name]: Show timer status via systemctl, including short IDs, names, and disabled state. Optional job ID or name to show a single job.
  • -C: Interactively clean up elapsed one-time timers (removes unit files from disk).

Key functions: parseTime (time spec → OnCalendar), _writeUnitFiles (shared service+timer creation; 4th param job_type selects timer vs service path), createJob/createJobFromEdit (thin wrappers), editJobs (crontab-style edit with diff-and-apply), getManagedUnits (find tagged units by type), getManagedServiceJobs (find service-only jobs by # SYSTAB_TYPE=service marker), isJobService (detect service vs timer job), cleanJobs (remove elapsed one-time timers), disableJob/enableJob (stop+disable / enable+start, branching on isJobService), writeNotifyLines (append ExecStopPost notification lines), buildFlagsString/parseFlags (convert between CLI options and flags format, including s flag), resolveJobId (resolve hex ID or name to hex ID, accepts service-only jobs).

Testing

./test.sh

Runs 81 tests against real systemd user timers and services covering job creation, service creation, job names, status, logs, disable/enable, notifications, time format parsing, error cases, and cleanup. All test jobs are cleaned up automatically via trap.

Tests require a real systemd user session (systemctl --user) and cannot run in containers. CI runs ShellCheck only; tests are enforced locally via a pre-commit hook that also updates badges/tests.json.

After cloning, enable the hooks: git config core.hooksPath .githooks

Notes

• ShellCheck can be used for linting: shellcheck systab.
• Edit mode uses | as the field delimiter (not tabs or spaces) to allow multi-word schedules. Flags use : after the ID (e.g., a1b2c3:n=backup,i,o,e=user@host). Service jobs use the literal string service as the schedule column.
• Flags (s = service, i = desktop, o/o=N = include output, e=addr = email, n=name = job name) are persisted as # SYSTAB_FLAGS=... comments in service files. Names are additionally stored as # SYSTAB_NAME=... comments. Service jobs are additionally tagged with # SYSTAB_TYPE=service. ExecStopPost= lines use $SERVICE_RESULT/$EXIT_STATUS for status-aware messages. Unit file printf format strings must use %%s (not %s) since systemd expands %s as a specifier before the shell runs.
• Journal logs are queried with USER_UNIT OR SYSLOG_IDENTIFIER to capture both systemd messages and command output.
• showStatus uses systemctl show -p ActiveState,SubState (not is-active) for service jobs to correctly report states like activating that is-active would misreport as inactive.
• daemon-reload must run before enable/start for new service units; it is called inside _writeUnitFiles for the service path.