Caffeinate Computer

caffeinate — keep the Mac awake

macOS ships caffeinate. Use it. No daemons, no apps, no half-open laptops in airports.

Platform check

If uname is not Darwin, say so and stop:

> Not macOS — caffeinate is a macOS-only tool. On Linux, use systemd-inhibit, caffeine, or xset s off -dpms depending on environment.

The three patterns

Pick based on what the user is doing.

1. Tie wakefulness to a running process (preferred)

When there's already a PID — a running claude session, build, sync, agent loop:

caffeinate -i -w  &

• -i prevents idle sleep
• -w exits caffeinate when that PID exits
• & backgrounds it so the shell stays usable

Find the PID with pgrep -f claude or echo $$ from inside the long-running shell.

2. Wrap a command

When launching the long task fresh:

caffeinate -i 

caffeinate exits the moment the wrapped command exits. Cleanest pattern — no orphan processes, no manual cleanup.

3. Time-bounded, full lockout (overnight runs, lid closed)

caffeinate -dimsu -t 28800   # 8 hours

• -d display sleep
• -i idle sleep
• -m disk sleep
• -s system sleep (only effective on AC power)
• -u declares user activity (resets idle timer for 5s, useful as a one-shot nudge)
• -t auto-expire so it can't run forever

Use -s only when plugged in. On battery, drop it: caffeinate -dim -t .

Lid-closed (clamshell) caveat

caffeinate alone does not keep a MacBook awake with the lid shut on battery. For true clamshell-while-unplugged you need external power + display + input, or a tool like InsomniaX/Amphetamine. Tell the user this if they ask about closing the lid.

Picking the flag set

| Goal | Flags | |---|---| | Just stop idle sleep during a task | -i | | Also keep the display on (watching output) | -di | | Long unattended run, plugged in | -dimsu -t | | Tied to a specific PID | add -w |

man caffeinate has the full list. Don't invent flags.

What to do for the user

1. Confirm macOS (uname → Darwin).
2. Ask (or infer) whether there's a PID to attach to, a command to wrap, or just a time window.
3. Build the exact one-liner from the patterns above. Show it. Run it if they want, otherwise hand it over.
4. Mention how to stop it: kill %1 for backgrounded &, or it self-exits when the PID/command/timer ends.

Keep it tight. One command, one line of explanation.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: jtsternberg
• Source: jtsternberg/claude-plugins
• License: MIT

Install and usage instructions live in the source repository linked above.