-lightgrey.svg){kind=icon}
The missing control knob for your Mac's SMC.
smctl is an open-source, CLI-first tool for controlling the hardware your Mac normally manages for you — fan speed, battery charging, and power telemetry — straight from the terminal.
smctl 是一个开源、命令行优先的 Mac 硬件控制工具：风扇曲线、电池充电限制、温度/功耗遥测——这些 macOS 不开放的控制能力，一条命令搞定。
English | 中文文档
$ smctl battery maintain 70-80 # keep the battery between 70% and 80%
$ smctl fan profile quiet # custom fan curve, stays silent until hot
$ smctl sensors --watch # live temperatures, fan RPM, package power- Your battery ages fastest at 100%. macOS only offers an opaque, ML-driven "Optimized Charging" and a single fixed 80% option. smctl gives you an explicit, deterministic charge limit with a sailing range — set it once, sync it in your dotfiles.
- Apple Silicon Macs expose no fan control at all. No official API, no third-party CLI — smctl implements manual fan targets and declarative fan curves on Apple Silicon, with a built-in thermal safety guard.
- Headless Macs deserve first-class tooling. Running a Mac mini as a home server? Every feature works over SSH, every command has
--jsonoutput for scripting.
| Command | What it does |
|---|---|
smctl sensors [--watch] [--json] |
Temperatures by sensor group, fan RPM/mode, battery, package power |
smctl battery status |
Charge level, charging state, configured limit |
smctl battery maintain 80 / 70-80 / stop |
Charge limit with dead-band (no charge/discharge flapping) |
smctl battery charge 90 / discharge 40 |
One-shot top-up or supervised discharge |
smctl fan status |
Per-fan actual/target/min/max RPM and control mode |
smctl fan set 2500 [--fan N] |
Manual fan target |
smctl fan profile quiet|full|auto|<custom> |
Declarative fan curves (TOML), hysteresis + slew-rate limited |
smctl daemon install|uninstall|status|ping |
Manage the privileged helper |
Policies live in /etc/smctl/config.toml — declarative, diffable, dotfiles-friendly.
$ brew install leaperone/smctl/smctl
$ sudo smctl daemon installOr tap once and use short names from then on:
$ brew tap leaperone/smctl
$ brew install smctl # later: brew upgrade smctl$ git clone https://github.com/leaperone/smctl && cd smctl
$ swift build -c release
$ sudo .build/release/smctl daemon installEach release ships a zip with smctl + smctld, Developer ID signed and notarized by Apple.
Charge limiting and fan control are applied by smctld, a root LaunchDaemon. The CLI talks to it over XPC; reading sensors needs no daemon and no root.
Controlling fans and charging from userspace demands paranoia. smctl treats these as first-class invariants:
- Never leave a brick. Uninstalling, stopping, or killing the daemon restores system control of fans and charging — enforced by termination hooks, startup reconciliation, and launchd restart.
- Thermal safety guard. While fans are under manual control, smctl monitors all temperature sensors every second. Sustained readings above the ceiling (default 100 °C, hard-capped at 105 °C, cannot be disabled) force fans back to system control and latch out manual control until things cool down. Losing temperature visibility counts as unsafe.
- Verified writes. Every SMC write is read back and verified (with a settle window for firmware that applies writes asynchronously) — failures surface as errors, never as silent no-ops.
- Graceful degradation. If a macOS update changes SMC behavior, affected features degrade to read-only with an explicit message instead of pretending to work.
- Apple Silicon Macs, macOS 14+.
- Fan control fully verified on M4 Mac mini (direct-write path). The diagnostic-unlock fallback path for machines that need it (some MacBook Pro generations) is implemented per published research but needs more real-hardware coverage — reports welcome.
- Battery charge control targets the same SMC keys used by established tools (pre-Tahoe and macOS 26 key sets, runtime-detected); broader machine coverage is in progress.
- Intel Macs: not yet (sensors are read-only there for now).
Capability detection is done at runtime — on unsupported hardware, commands tell you exactly what's unavailable rather than failing silently.
| smctl | macOS built-in | AlDente | Macs Fan Control | stats | |
|---|---|---|---|---|---|
| CLI / scriptable | ✅ | — | — | — | — |
| Battery charge limit | ✅ custom range | 80% fixed | ✅ | — | — |
| Fan control (Apple Silicon) | ✅ curves | — | — | ✅ GUI only | — |
| Declarative config | ✅ TOML | — | — | — | — |
| Open source | ✅ MIT | — | — | — | ✅ |
- Homebrew tap, then homebrew-core
smctl battery calibrate, thermal-throttling visibility (smctl power)- Menu bar app (the daemon already speaks XPC; a GUI is just another client)
- 中文项目文档 — vision, research notes, and roadmap (Chinese)
- Architecture & design (Chinese)
- Field notes: M4 Mac mini — real-hardware findings, including SMC asynchronous-write behavior (Chinese)
smctl writes to your Mac's System Management Controller. The safety mechanisms above are engineered conservatively, but you use it at your own risk — especially manual fan control under sustained load.