Real-time system metrics in your zsh right prompt — power, battery, CPU, CPU temp, fan speed, memory, and network I/O, glanceable at a glance.

PowerLens is a lightweight Oh-My-Zsh plugin that embeds live system metrics into RPROMPT. A single background daemon collects all data every 2 seconds; the prompt reads a cached JSON file on each precmd — adding less than 5ms to prompt render time regardless of how many terminal windows you have open.

Each metric is colored independently. Thresholds are fully configurable.

git clone https://github.com/luyangkk/powerlens.git \
  ~/.oh-my-zsh/custom/plugins/powerlens

Add powerlens to your plugins list in ~/.zshrc:

plugins=(... powerlens)

Reload your shell:

source ~/.zshrc

If macOS blocks the pre-compiled binary (Gatekeeper), build it yourself — requires Go 1.21+:

cd ~/.oh-my-zsh/custom/plugins/powerlens
make install

Or remove the quarantine flag from the pre-built binary:

xattr -d com.apple.quarantine bin/powerlens-fetch-arm64   # Apple Silicon
xattr -d com.apple.quarantine bin/powerlens-fetch-amd64   # Intel

All options are set in ~/.zshrc before the plugins=(...) line.

POWERLENS_MODE=compact        # compact | full
POWERLENS_COLOR_MODE=multi    # multi   | alert

compact (default):

⚡38W 🔋87% ⚙34% 🌡55° 🌀1200 🧠62% ↑1.2M↓3.8M

full:

⚡ 38.4W 🔋 87% ⚙ 34.2% 🌡 55.0°C 🌀 1200RPM 🧠 62.1% ↑ 1.2MB/s ↓ 3.8MB/s

POWERLENS_SHOW_BATTERY=true   # true | false
POWERLENS_SHOW_CPU=true
POWERLENS_SHOW_TEMP=true
POWERLENS_SHOW_FAN=true       # hidden automatically on fanless Macs
POWERLENS_SHOW_MEM=true
POWERLENS_SHOW_NET=true

POWERLENS_NET_IFACE=default   # default | wifi | ethernet

The interface type is shown as an icon prefix on the network display:

• 📶 Wi-Fi
• 🔌 Ethernet
• 🌐 Other / VPN

POWERLENS_REFRESH=2           # seconds between daemon polls

Each metric has three thresholds that divide the four color levels (Idle → Light → Moderate → Peak):

# Power (Watts)
POWERLENS_THRESH_POWER_IDLE=10
POWERLENS_THRESH_POWER_LIGHT=30
POWERLENS_THRESH_POWER_MODERATE=50

# CPU (%)
POWERLENS_THRESH_CPU_IDLE=30
POWERLENS_THRESH_CPU_LIGHT=60
POWERLENS_THRESH_CPU_MODERATE=85

# Memory (%)
POWERLENS_THRESH_MEM_IDLE=50
POWERLENS_THRESH_MEM_LIGHT=70
POWERLENS_THRESH_MEM_MODERATE=85

# CPU Temperature (°C)
POWERLENS_THRESH_TEMP_IDLE=50
POWERLENS_THRESH_TEMP_LIGHT=70
POWERLENS_THRESH_TEMP_MODERATE=85

# Fan Speed (RPM)
POWERLENS_THRESH_FAN_IDLE=2000
POWERLENS_THRESH_FAN_LIGHT=3500
POWERLENS_THRESH_FAN_MODERATE=5000

Default values are tuned for Apple Silicon MacBooks. Adjust for your machine.

In alert mode all metrics render in neutral gray (#aaaaaa) until a single threshold is crossed, then switch to orange (#FF9500):

POWERLENS_ALERT_POWER=50      # W
POWERLENS_ALERT_CPU=80        # %
POWERLENS_ALERT_MEM=85        # %
POWERLENS_ALERT_TEMP=80       # °C
POWERLENS_ALERT_FAN=4000      # RPM

┌──────────────────────────────────────────────────────┐
│  Terminal 1      Terminal 2      Terminal 3           │
│  (precmd)        (precmd)        (precmd)             │
│      │               │               │               │
│      └───────────────┴───────────────┘               │
│                      │                               │
│              read metrics.json                       │
│              (only on mtime change)                  │
│                      │                               │
│      ┌───────────────▼──────────────────────┐        │
│      │  powerlens-fetch  (singleton daemon)  │        │
│      │  · IOKit → power, battery             │        │
│      │  · IOKit/SMC → CPU temp, fan speed    │        │
│      │  · gopsutil → CPU, memory, network    │        │
│      │  · writes metrics.json every 2s       │        │
│      └──────────────────────────────────────┘        │
└──────────────────────────────────────────────────────┘

• The daemon is started by the first shell and shared across all subsequent shells (PID file singleton).
• Each precmd checks the file modification time — the JSON is re-parsed only when it actually changes.
• The last shell to exit kills the daemon.

• macOS 12 (Monterey) or later
• Zsh 5.8+
• Oh-My-Zsh

make arm64      # Apple Silicon
make amd64      # Intel
make universal  # Universal binary (lipo)
make all        # Both arm64 + amd64
make clean      # Remove built binaries

• Historical mini-graph using Unicode Braille (⣀⣄⣆⣇⣗⣷⣿) in expanded mode
• powerlevel10k geometry integration
• Multiple battery support (MagSafe + Thunderbolt)
• CI notarization via GitHub Actions

Contributions are welcome! Please read CONTRIBUTING.md before submitting a pull request.

MIT — see LICENSE for details.