Keep Your Mac Awake, Then Have It Tell You It Finishedcaffeinate and say (2026 Edition)

Introduction

Updated October 23, 2026: Rechecked on macOS Golden Gate (27), released in September 2026. Nothing has changed in how caffeinate and say work. This update corrects the description of say -o output formats to match the list on a real Mac, and adds the current settings name for adding voices, a way to confirm the effect with pmset, and the Shortcuts changes.

Hello everyone! Today I want to introduce two "hidden gem" commands that make your Mac more convenient — and a little more fun to use. The first is caffeinate. The second is say.

Both ship standard with current macOS, including macOS Golden Gate (27), released in September 2026 — no extra installs, no menu-bar utility app required. On a Mac running macOS 27.0.1, the options and man pages were the same as before.^[3] Learning these two commands alone removes a surprising amount of everyday friction.

1. caffeinate — The Magic That Keeps Your Mac Awake

1-1. Purpose and Function

Mac automatically enters sleep mode after a period of inactivity — great for battery life, but inconvenient when you're:

• Running a long download or build
• Executing a server process or batch script
• Displaying slides during a presentation or meeting
• Streaming video or signage on an external display

That's where caffeinate comes in.^[1] True to its name, it keeps your Mac awake for as long as the conditions you specify remain true.

1-2. Basic Usage

Open Terminal and type:

caffeinate

That's it — your Mac won't sleep until you close the terminal or press Ctrl + C. Called with no arguments, caffeinate defaults to behavior equivalent to -i, preventing idle system sleep.

1-3. Mastering the Options

caffeinate has several flags you can combine to control precisely what — and for how long — stays awake.

Some common combinations:

• Prevent sleep for just 30 minutes

  caffeinate -u -t 1800

-t takes seconds (1800 seconds = 30 minutes).

• Prevent sleep only while a specific command runs

  caffeinate -s curl -O https://example.com/bigfile.zip

Once curl finishes, sleep is automatically re-allowed. Because it wraps a process, this pattern works equally well for long builds or rsync transfers.

• Wait for an already-running process to finish

  caffeinate -w 1234

Prevents sleep until the process with PID 1234 exits — handy when pairing with a heavy job you already launched in the background.

• Confirm that it is actually working

  pmset -g assertions | grep caffeinate

While caffeinate is running, an assertion (a declaration that blocks sleep) named "caffeinate command-line tool" appears in the output.^[4]

According to the man page, -u expires after about five seconds unless you add -t. When you pass a command for caffeinate to run, -t and -w are not used.

Figure 1: caffeinate's core flags at a glance — pick the display, system, or disk layer you want to keep awake.

1-4. When to Use It

• Running large overnight downloads or backups
• Keeping a Zoom, Google Meet, or Teams call visible without the screen dimming
• Looping slides or video on an external display
• Running CI builds or long npm/yarn tasks locally on your Mac

It's a small but powerful ally against the classic "oops, my Mac fell asleep" moment.

2. say — Let Your Mac Talk

2-1. Purpose and Function

Next up is the say command^[2] — it literally makes your Mac talk. Originally part of macOS's accessibility features for visually impaired users, it also doubles as a fun tool for learning and for scripted notifications.

2-2. Basic Usage

Try this in Terminal:

say "Hello, World!"

Your Mac speaks the phrase aloud. It handles Japanese just as naturally:

say "おはようございます。今日も元気にいきましょう。"

2-3. Changing Voices and Saving to a File

You can add voices under System Settings → Accessibility → Read & Speak, using the info button next to “System voice” (as labeled in macOS 27).^[5] List the voices already installed with say -v ?.

say -v Kyoko "おはよう"
say -v Samantha "Good morning"
say -v "?"

Adjust speaking rate (words per minute) with -r:

say -r 220 "This reads a little faster than normal"

You can also save speech to a file. AIFF is the default, and WAVE, CAF, m4a (AAC), FLAC, and other formats are also available. Supported formats vary by voice and OS version, so check the list with --file-format="?" below. MP3 is not in that list, and direct MP3 output is not supported. On macOS 27.0.1, using a .mp3 extension produced no error but left an unplayable file of only a few dozen bytes. If you need MP3, export to a supported format first, then convert with afconvert or ffmpeg.

# Writes AIFF (the default)
say "This is a test recording" -o test.aiff

# Explicit format (m4af, caff, WAVE, etc. are also valid)
say "This is a test recording" -o test.m4a --file-format=m4af

# FLAC is also inferred from the extension
say "This is a test recording" -o test.flac

# List every writable format on your system
say -o /dev/null --file-format="?" "list"

Figure 2: say handles both Japanese and English speech. AIFF is the default output, and WAVE, CAF, m4a, FLAC, and more are available — converting to MP3 requires an extra step.

2-4. When to Use It

• Language learning (hear English pronunciation read aloud)
• Narration-style sound effects during a presentation
• A spoken notification when a long-running task finishes
• A quick sanity check for read-aloud content when a screen reader isn't available

Add say "Backup complete" to the end of an automated job, and it becomes a genuinely useful voice notification.

3. Advanced: Combining caffeinate and say

3-1. Completion Notifications for Long Jobs

Combine the two and you get an automation that "stays awake while working, and tells you out loud when it's done."

caffeinate -s ./long_process.sh && say "Processing complete"

• caffeinate -s prevents sleep
• say announces completion by voice

It becomes a genuine "work buddy."

3-2. Wiring It Into a Shell Script

Add this pattern to your build or test wrapper scripts so you notice completion even when you've stepped away from the screen.

#!/bin/bash
set -e
caffeinate -dims &
CAFFEINATE_PID=$!

npm run build
npm test

kill "$CAFFEINATE_PID" 2>/dev/null
say "Build and tests are complete"

caffeinate -dims chains flags together to block display, system, and disk idle sleep at once. It runs in the background and gets killed once the work finishes.

Figure 3: caffeinate blocks sleep, then say announces completion by voice — together they form a reliable work buddy.

4. A Few More Built-In Commands Worth Knowing

Beyond caffeinate and say, macOS ships with a handful of other commands that are easy to miss but genuinely useful alongside them.

• pbcopy / pbpaste: Pipe standard input/output to and from the clipboard. cat file.txt | pbcopy copies a file's contents directly.
• open -a "AppName": Open any app, file, or URL from Terminal. open . to reveal the current directory in Finder is a classic.
• screencapture -T 5 shot.png: Takes a screenshot after a 5-second delay. Add -i for interactive selection or -c to copy straight to the clipboard.
• shortcuts run "Shortcut Name": Run a saved Shortcuts (the successor to Automator) workflow with a single line from Terminal. In macOS 27, the four subcommands — run, list, view, and sign — are unchanged. The app itself gained the ability to create shortcuts from a natural-language description (Apple Intelligence required) and an automation triggered when a screenshot is saved, which also works on the Mac.^[6]

Quick summary: knowing caffeinate, say, pbcopy/pbpaste, open, screencapture, and shortcuts run together removes a lot of situations where you'd otherwise reach for the mouse.

Conclusion

Today we covered a few genuinely useful commands that ship standard with Mac but are surprisingly unknown.

1. caffeinate: Keeps your Mac awake — great for long tasks and meetings
2. say: Makes your Mac talk — useful for learning, notifications, and presentation flair
3. Combining both: Sleep prevention plus a spoken completion notice makes a solid "work buddy"
4. Neighboring commands: pbcopy/open/screencapture/shortcuts run round out the toolkit

Every one of these is a small trick that makes daily life on the Mac a bit smoother. Open Terminal and give them a try.