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Two terminal blocks for the same busy volume: diskutil eject reporting the unmount was dissented by PID 16961 (/usr/bin/tail) with dissenter parent PPID 16959 (/bin/zsh), and umount reporting only Resource busy -- try 'diskutil unmount'

“Disk Not Ejected Properly” on Mac: What Causes It and How to Eject Safely

by Marcus Reeve
September 17, 2026July 20, 2026

The “Disk Not Ejected Properly” notification appears after the fact: a volume that macOS still had mounted is suddenly gone. Pulling a cable is the obvious way to cause it, but it also shows up…

Two terminal panels: launchctl list showing com.apple.Finder with last exit status -15 after killall Finder and -9 after killall -9 Finder, and ps output showing state S for sleeping next to the man ps definition of U as uninterruptible wait

Finder Not Responding on Mac: How to Relaunch It and Find the Cause

by Marcus Reeve
September 14, 2026July 20, 2026

Finder stops redrawing, the spinning wheel appears, and clicking a window does nothing. Relaunching Finder is the standard first move, and it is safer than force quitting a regular app: Finder is managed by launchd,…

A macOS terminal running codesign -dvvv on Calculator.app, showing Identifier com.apple.calculator and an Authority chain of Software Signing, Apple Code Signing Certification Authority, and Apple Root CA, with notes to read the signer, verify integrity, and check notarization

How to Check an App’s Code Signature on a Mac with codesign

by Marcus Reeve
September 11, 2026July 19, 2026

When you download an app outside the App Store, codesign is the built-in way to check who actually signed it and whether the copy on disk has been tampered with. It reads the signature that…

A macOS terminal running nc -zv host 22 returning Connection to host port 22 succeeded, and nc -zv host 9 returning connectx to host port 9 failed refused, with notes to scan a range, use -l to listen, and that netcat is built in

How to Use netcat (nc) on a Mac to Test Ports

by Marcus Reeve
September 8, 2026July 19, 2026

Every Mac already has nc — netcat — so there is nothing to install to check whether a port is open, scan a short range, or stand up a throwaway listener to test a connection.…

The osascript command shown as osascript -e 'display notification Build done' on a dark terminal, with labels for posting notifications, showing dialogs and reading input, and controlling other apps from the Mac Terminal

How to Use osascript: Run AppleScript from the Mac Terminal

by Marcus Reeve
September 5, 2026July 19, 2026

The osascript command runs AppleScript — and JavaScript — straight from the Terminal, which makes it the bridge between a shell script and the Mac’s GUI layer. It is how a shell script pops a…

Two archive file listings compared: a Finder Compress zip containing project a.txt and b.txt plus __MACOSX slash dot-underscore shadow files, next to a clean zip -X archive containing only project a.txt and b.txt

How to Zip Files on a Mac Without the __MACOSX Junk

by Marcus Reeve
September 2, 2026July 19, 2026

There are two easy ways to make a zip on a Mac: right-click a folder in the Finder and choose Compress, or run zip in the Terminal. Both work. The problem shows up on the…

The sips command on macOS shown as sips -s format jpeg star dot HEIC --out converted slash, with notes that it converts HEIC to JPG, PNG and TIFF, resizes with -Z 800, and batches a whole folder from the Terminal

The sips Command: Convert and Resize Images from the Mac Terminal

by Marcus Reeve
August 30, 2026July 19, 2026

Every Mac ships with sips — Scriptable Image Processing System — so there is nothing to install to convert, resize, or rotate an image from the Terminal. For a single photo, the Finder is honestly…

A crontab line 30 3 * * 1 broken into labeled fields (minute, hour, day, month, weekday) followed by the command, with notes that macOS cron needs Full Disk Access, runs with a minimal PATH, and is started on demand by launchd

How to Use crontab on macOS (and Why Cron Jobs Don’t Run)

by Marcus Reeve
August 28, 2026July 19, 2026

cron still works on macOS. The crontab command is built in — there is nothing to install — and it schedules jobs with the same five-field syntax you would use on Linux. The trouble Mac…

macOS terminal showing three rsync examples: rsync -av src/ backup/ to copy a folder, rsync -av --delete src/ backup/ to mirror it, and rsync -avz proj/ user@host:proj/ to sync over SSH, with a flag legend for -a archive, -v verbose, -z compress, -P progress and resume, and -n dry-run.

How to Use rsync on macOS: Examples and Common Flags

by Marcus Reeve
August 25, 2026July 19, 2026

rsync copies and syncs folders efficiently — it only transfers the parts that changed, which makes it ideal for backups and for keeping two machines in step. It’s built into macOS, so there’s nothing to…

macOS terminal showing ipconfig getifaddr en0 returning a local IP 192.168.1.42, with a table: any interface reliably via ipconfig getifaddr with route get default, public IP via curl api.ipify.org, and a note that the Linux ip addr and hostname -I do not exist on macOS.

How to Find Your IP Address from the macOS Terminal

by Marcus Reeve
August 23, 2026July 19, 2026

The macOS way to find your IP address from the terminal isn’t the Linux ip addr or hostname -I — neither of those exists here. It’s ipconfig getifaddr, with one wrinkle: you have to point…