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Two terminal blocks from the same machine: pmset -g batt reporting 76%, AC attached and not charging, and system_profiler reporting Cycle Count 21, Condition Normal, Maximum Capacity 100% with a 90W adapter connected

Mac Charging Stops at 80%? That Is macOS Protecting the Battery

by Marcus Reeve
October 5, 2026July 20, 2026

A Mac that sits at 80% and reports “not charging” looks like a fault, and it is almost always deliberate. Modern macOS holds the charge back to slow the battery’s chemical ageing — a battery…

Output of mdutil -s -a listing five volumes, three with Indexing enabled and two showing Indexing disabled and Indexing and searching disabled, with the user name and two volume names replaced by placeholders

Spotlight Not Working on a Mac: Check This Before Rebuilding the Index

by Marcus Reeve
October 2, 2026July 20, 2026

When Spotlight stops finding things, the usual advice is to rebuild the index. That works often enough to keep getting repeated, and it is also the most expensive thing you can do — a full…

Terminal output showing dd failing with No space left on device, above docker system df reporting 53.15GB of build cache with 46.98GB reclaimable and an ACTIVE count of zero, alongside 45.36GB of images and 5.511GB of local volumes

“No Space Left on Device” on a Mac: Where the Space Went

by Marcus Reeve
September 30, 2026July 20, 2026

No space left on device is an honest error from the kernel: a write was refused because the filesystem had nowhere to put it. The disk is full. What makes it confusing on a Mac…

Two terminal blocks: ifconfig awdl0 showing the interface UP, RUNNING with status active, and defaults read com.apple.sharingd DiscoverableMode returning Everyone with the alternatives Contacts Only and Off noted alongside

AirDrop Not Working on a Mac: Check the Interface It Runs On

by Marcus Reeve
September 27, 2026July 20, 2026

AirDrop fails in a way that gives you nothing to work with: the other device simply is not there. No error, no explanation, just an empty sharing sheet. The reason it is so opaque is…

Two terminal blocks: log show --last boot printing the === system boot marker that delimits one startup from the next, and sysctl kern.safeboot returning 0 alongside system_profiler reporting Boot Mode: Normal

Mac Stuck on the Loading Screen: How to Narrow It Down

by Marcus Reeve
September 23, 2026July 20, 2026

A Mac sitting on the Apple logo with a progress bar that has not moved for twenty minutes is the hardest kind of problem to troubleshoot, because the machine cannot tell you anything while it…

Four terminal error lines with the reporting program highlighted: zsh: permission denied: ./hello.sh, cd: permission denied: somedir, cat: /etc/sudoers: Permission denied, and touch: /usr/testfile: Operation not permitted

“zsh: permission denied” on macOS: The Three Causes and Their Fixes

by Marcus Reeve
September 20, 2026July 20, 2026

zsh: permission denied looks like one error, and it is really three. The shell says it when a file has no execute bit, when the thing you pointed at cannot be executed at all, and…

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.…