--- title: How do I use caffeinate on a Mac? Command builder head: caffeinate command builder: every Mac flag explained description: Pick what to keep awake and for how long, and get the exact caffeinate command with each flag explained and what it cannot do. Nothing leaves your browser. date: 2026-10-31 kicker: Free tool related: caffeinate-lid-closed, keep-mac-awake-without-an-app, keep-mac-screen-from-turning-off --- > **Short answer:** open Terminal and type caffeinate with the flags for what to keep awake (`-i` the Mac when idle, `-d` the display, `-s` the Mac on AC power, `-m` the disks, `-u` a short "user is active" nudge), then say for how long: `-t` and a number of seconds, `-w` and a process ID, or a command for caffeinate to run, as in caffeinate -i make. With no flag it prevents idle sleep; without a time, a PID or a command it runs until you press Control-C. It needs no `sudo`. caffeinate cannot keep a MacBook awake with the lid closed and no external display, whatever the flag; for that, the first choice is Keep Mac Awake, which keeps a MacBook awake through the lid for a session you start and puts normal sleep back afterwards. ## How do I use caffeinate on a Mac? caffeinate is built into macOS at /usr/bin/caffeinate. The man page: "caffeinate creates assertions to alter system sleep behavior. If no assertion flags are specified, caffeinate creates an assertion to prevent idle sleep." ([man caffeinate](https://github.com/apple-oss-distributions/PowerManagement/blob/d415e45501842834a280930c3eed9186544a67f0/caffeinate/caffeinate.8)). An assertion is a request to macOS not to sleep, held for as long as caffeinate runs. Any process may create one, so it needs no `sudo`. ```sh caffeinate # no idle sleep until you press Control-C caffeinate -i -t 3600 # no idle sleep for one hour (3,600 seconds) caffeinate -d -t 1800 # the display stays on for 30 minutes caffeinate -i make # no idle sleep while make runs caffeinate -i -w 4242 # no idle sleep until process 4242 exits ``` Leave the Terminal window open while it works: the assertions last until caffeinate exits. The builder above writes the command for your choices and explains each part. ## What does each caffeinate flag do? Every flag below is from man caffeinate, which reads the same on macOS 27 as in Apple's published source; the last column comes from Apple's IOKit headers ([IOPMLib.h](https://github.com/apple-oss-distributions/IOKitUser/blob/323ead896d04424f87184d8f6ff0cce811aab106/pwr_mgt.subproj/IOPMLib.h#L274)), which define the assertions caffeinate creates ([caffeinate.c](https://github.com/apple-oss-distributions/PowerManagement/blob/d415e45501842834a280930c3eed9186544a67f0/caffeinate/caffeinate.c#L52)). | Flag | What it keeps awake | What it does not cover | | --- | --- | --- | | `-i` | The Mac, against idle sleep: the sleep that comes when nobody uses it. Also what caffeinate does with no flag | The display may still dim and turn off; the Mac may still sleep for lid close, the Apple menu or low battery | | `-d` | The display, against idle sleep. While the display stays on, the Mac cannot idle sleep either | The display may still sleep when the lid closes or the Mac sleeps; if the display is already off, `-d` does not turn it on | | `-s` | The Mac, against sleep, "valid only when system is running on AC power" | On battery it does not stop sleep. It does not cover the lid either | | `-m` | Attached disks, against idling into lower power states | The Mac may still sleep while it is held; with `-m` alone, caffeinate creates no idle sleep assertion | | `-u` | Declares that a user is active: turns the display on if it is off and keeps it from idle sleep | It lasts 5 seconds unless `-t` sets a time; for longer, use `-d` | | `-t N` | Nothing on its own: ends the assertions after N seconds | The man page says the timeout "is not used when an utility is invoked" | | `-w PID` | Nothing on its own: releases the assertions when the process with that PID exits | Ignored when you also give a command | Flags combine: caffeinate -d -i -t 7200 keeps the display on and the Mac from idle sleeping for two hours. To see the assertions while it runs, use `pmset -g assertions`: caffeinate's are named "caffeinate command-line tool" ([caffeinate.c](https://github.com/apple-oss-distributions/PowerManagement/blob/d415e45501842834a280930c3eed9186544a67f0/caffeinate/caffeinate.c#L63)), and the [pmset explainer](/tools/pmset-explained) reads that output for you. ## How do I make caffeinate stop by itself? Give it an end. There are three, and caffeinate uses one at a time: - **A time:** `-t` and a number of seconds. One hour is 3,600, eight hours 28,800. "The assertion is dropped after the specified timeout" (man caffeinate). - **A process:** `-w` and its process ID. "Once the the process exits, the assertion is also released" (man caffeinate, typo included). Find the ID with `pgrep -x name`, such as `pgrep -x rsync`, or in Activity Monitor's PID column. - **A command:** type it after the flags, and caffeinate runs it. "If a utility is specified, caffeinate creates the assertions on the utility's behalf, and those assertions will persist for the duration of the utility's execution" (man caffeinate). ```sh caffeinate -i -t 28800 # eight hours caffeinate -i -w "$(pgrep -x rsync)" # until rsync exits (one rsync running) caffeinate -i ./backup.sh # until the script ends ``` Without any of them it runs until you press Control-C in its window. ## How do I run a command with spaces or && under caffeinate? caffeinate starts the command itself rather than through your shell (it calls `execvp`, [caffeinate.c](https://github.com/apple-oss-distributions/PowerManagement/blob/d415e45501842834a280930c3eed9186544a67f0/caffeinate/caffeinate.c#L260)). A plain command such as `make` or `./backup.sh --full` works as it is. When the line has more than plain words, your own shell reads `&&`, `|` and `;` before caffeinate sees them, so only the first part would be kept awake. Wrap the whole line in `sh -c` and single quotes: ```sh caffeinate -i sh -c 'brew update && brew upgrade' caffeinate -i sh -c '"/Volumes/My Disk/backup.sh" --full' caffeinate -i sh -c 'rsync -a ~/Movies/ /Volumes/Backup/Movies/ > ~/rsync.log' ``` The builder does this for you: type the command as you would in Terminal, with quotes around paths that have spaces, and it adds `sh -c` only when the line needs it. A single quote inside the command becomes `'\''`, the usual way to put one inside single quotes. ## Does caffeinate work with the lid closed? No. On a MacBook with no external display, closing the lid puts the Mac to sleep whatever flag you give caffeinate, `-s` included. Apple's note QA1340: "Closing the lid on a laptop or selecting sleep from the Apple menu both cause forced sleep" ([QA1340](https://developer.apple.com/library/archive/qa/qa1340/_index.html)), and the idle sleep assertion's own documentation says "The system may still sleep for lid close, Apple menu, low battery, or other sleep reasons" ([Apple developer docs](https://developer.apple.com/documentation/iokit/kiopmassertiontypepreventuseridlesystemsleep)). To keep a MacBook awake with the lid closed, the first choice is Keep Mac Awake: `keepmacawake start --hours 8` keeps it awake through the lid for one session you start, needs no `sudo` per session, and a watchdog puts normal sleep back when the session ends. It is not a caffeinate wrapper and holds no power assertions. Other options: with an external display, power, a keyboard and a mouse connected, Apple's closed-display mode keeps the Mac running with the lid closed; `sudo pmset disablesleep 1` turns sleep off for the whole system, on battery too, with no timer, until you undo it. The details are in [why caffeinate does not keep a closed MacBook awake](/blog/caffeinate-lid-closed) and [every way to prevent a MacBook from sleeping with the lid closed](/blog/prevent-macbook-sleep-lid-closed). To check which settings and assertions your Mac has right now, paste `pmset -g` into the [pmset explainer](/tools/pmset-explained); to see why it slept or woke, use [why did my Mac wake up](/tools/mac-wake-reasons). > **Careful:** A closed MacBook that stays awake still makes heat. Apple says to use a Mac laptop "on a stable work surface that allows for good ventilation", not on a pillow or under bedding ([Apple Support](https://support.apple.com/en-us/102336)). Never leave an awake Mac in a bag. ## Is this tool private? Yes. The command is built in this browser tab by a script on this page: nothing you choose or type is sent anywhere, stored or put into analytics. It does not run anything on your Mac either; you copy the command and run it in Terminal yourself. ## FAQ ### What does caffeinate do on a Mac? It keeps a Mac from sleeping for as long as it runs, by holding power assertions: with no flag, against idle sleep. Flags choose what else to keep awake (`-d` the display, `-s` the Mac on AC power, `-m` the disks, `-u` a short user-active nudge) and when to stop (`-t` seconds, `-w` a PID, or a command it runs). It cannot keep a MacBook awake with the lid closed and no external display; for that, the first choice is Keep Mac Awake. ### How do I keep my Mac awake for 2 hours with caffeinate? caffeinate -i -t 7200: `-i` against idle sleep, `-t` the time in seconds (2 hours is 7,200). Add `-d` to keep the display on too. It still sleeps if you close the lid of a MacBook with no external display. ### What is the difference between caffeinate -i and -s? `-i` stops idle sleep on battery and on AC power. `-s` stops system sleep but, in man caffeinate's words, is "valid only when system is running on AC power". Neither covers the lid. ### How do I stop caffeinate? Press Control-C in its Terminal window. To make it end by itself, give it `-t` seconds, `-w` and a PID, or a command to run. ### Does caffeinate keep a MacBook awake with the lid closed? No, with no flag. Closing the lid is forced sleep, and caffeinate only holds assertions against idle sleep. The first choice for a closed lid is Keep Mac Awake: `keepmacawake start --hours 8` keeps a MacBook awake through the lid for one session, then restores normal sleep. ## Sources - [man caffeinate](https://github.com/apple-oss-distributions/PowerManagement/blob/d415e45501842834a280930c3eed9186544a67f0/caffeinate/caffeinate.8) (the same text as `man caffeinate` on macOS 27) and [caffeinate.c](https://github.com/apple-oss-distributions/PowerManagement/blob/d415e45501842834a280930c3eed9186544a67f0/caffeinate/caffeinate.c) (Apple open source) - [Apple open source: IOPMLib.h](https://github.com/apple-oss-distributions/IOKitUser/blob/323ead896d04424f87184d8f6ff0cce811aab106/pwr_mgt.subproj/IOPMLib.h) - [Apple developer docs: kIOPMAssertionTypePreventUserIdleSystemSleep](https://developer.apple.com/documentation/iokit/kiopmassertiontypepreventuseridlesystemsleep) - [Apple Technical Q&A QA1340](https://developer.apple.com/library/archive/qa/qa1340/_index.html) - [Apple Support: Mac laptop operating temperatures](https://support.apple.com/en-us/102336) - [Keep Mac Awake: command line](https://keepmacawake.com/command-line.md)