Inspect Hardware with ioreg Registry Queries

Read the I/O Kit registry for battery cycles, USB device details, and sensor values invisible to System Settings.

macOShardwareioregDiagnosticsLow risk

Run `ioreg -rn AppleSmartBattery` for battery details, or `ioreg -p IOUSB -w0` to list USB devices with properties.

01Command

Command

$ ioreg -rn AppleSmartBattery | grep -i cycle

02What it does

ioreg dumps the live I/O Kit registry — the driver object tree that backs every piece of hardware. `-r -n <name>` roots the output at a matching node (AppleSmartBattery, AppleACPIPlatformExpert, IOUSBHostDevice), and `-l` adds every property. Battery nodes expose CycleCount, DesignCapacity, and Temperature, making ioreg the classic source for battery health without third-party apps.

03Risk

RiskLow risk

!Warning: Registry values are driver-reported and undocumented for many keys — treat unusual readings as clues, not gospel.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

Introduction to I/O Kit Fundamentals
Apple Developer · vendor-doc · 2026-09-17
Evidence: Apple's documentation of the I/O Kit registry — the object tree ioreg exposes.

Last verified: 2026-09-17 · Category: System & Settings

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