cron

cron is a skill for Claude Code, Codex from HKUDS/OpenOPC. It costs 18 tokens per session (403 once invoked), scanned A, original, MIT.

A scheduler for running commands automatically at set times or intervals. It uses the operating system’s cron service, which runs scheduled background jobs.

In plain words
What is it for?
Set recurring reminders, run commands every hour or on weekdays, schedule a job for a specific date and time, list existing jobs, and remove jobs.
Why use it?
It removes the need to remember recurring tasks or start one-time jobs manually. It also helps keep scheduled command output in log files.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/hkuds/openopc/cron
Any agent
npx skills add HKUDS/OpenOPC --skill cron
Clone the repo
git clone --depth 1 https://github.com/HKUDS/OpenOPC

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cron

README.md
[![agentmods](https://agentmods.dev/badge/skills/hkuds/openopc/cron.svg)](https://agentmods.dev/skills/hkuds/openopc/cron)
Your own site
<a href="https://agentmods.dev/skills/hkuds/openopc/cron"><img src="https://agentmods.dev/badge/skills/hkuds/openopc/cron.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 403 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00018 $0.00403
Opus 5 $0.00009 $0.00201
Sonnet 5 $0.00004 $0.00081
Haiku 4.5 $0.00002 $0.00040

Measured 4d ago against content hash 0f8adf93b0de, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cron scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.opc/skills/cron/SKILL.md · 61 lines

What it actually says

Cron

Schedule tasks using the system crontab via shell_exec.

List current cron jobs

crontab -l

Add a recurring job

(crontab -l 2>/dev/null; echo "*/20 * * * * echo 'Time to take a break!' >> /tmp/opc-reminders.log") | crontab -

Common schedules

Schedule Cron expression
Every 20 minutes */20 * * * *
Every hour 0 * * * *
Every day at 8am 0 8 * * *
Weekdays at 5pm 0 17 * * 1-5
Every Monday at 9am 0 9 * * 1

One-time scheduled task

Use at for one-time jobs:

echo "echo 'Meeting reminder' >> /tmp/opc-reminders.log" | at 14:30

Or schedule with a specific date:

echo "echo 'Deadline reminder' >> /tmp/opc-reminders.log" | at 10:00 2026-03-20

Remove a job

Edit the crontab directly:

crontab -e

Or filter out a specific job:

crontab -l | grep -v 'pattern-to-remove' | crontab -

Notes

  • Use full paths in cron commands (cron has a minimal $PATH).
  • Redirect output to a log file or /dev/null to avoid mail noise.
  • Check at availability: which at (install with apt install at if missing).
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 61 lines · 18 tokens per session scan A 0f8adf93b0de

Subscribe to this mod's changes

cron is a skill published in the GitHub repository HKUDS/OpenOPC (1,610 stars, last pushed today), licensed MIT. It adds 18 tokens to every session and 403 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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