Linux Fan Controller

A lightweight bash script for automatic temperature-based fan control arch\fedora based Linux systems with PWM fan support.

Features

Zero Dependencies - Pure bash, no Python or other interpreters needed
Lightweight - Only 2-5 MB memory footprint
Auto-Detection - Automatically finds all temperature sensors and fan controls
Multi-OS Support - Works on Arch Linux, Bazzite, Fedora, Ubuntu, and more
Smart Installer - Detects your distro and installs dependencies automatically
Systemd Integration - Runs as a service with auto-start on boot
Configurable - Easy-to-edit temperature thresholds and fan speeds
Safe - Resets fans to automatic mode on exit

Why This Exists

The Corsair AI Workstation 300 has a front performance button that controls fan profiles, but it only works with the Windows iCUE software. On Linux, you lose this functionality. This script provides automatic fan control based on system temperatures, giving you fine-tuned control over cooling and noise levels.

While Linux systems have built-in thermal protection and won't overheat without this script, custom fan control allows you to:

Reduce noise during light workloads
Increase cooling during heavy tasks
Set your own temperature/noise balance
React faster to temperature changes than BIOS curves

Requirements

Linux kernel with hwmon support (standard on all modern distros)
Bash 4.0 or higher (pre-installed on all modern Linux systems)
lm-sensors package (automatically installed by the installer)
PWM fan controls exposed via /sys/class/hwmon/
Root/sudo access for installation and fan control

Supported Distributions

The installer automatically detects and supports:

Arch Linux (and derivatives: Manjaro, EndeavourOS)
Bazzite (Fedora Atomic/immutable)
Fedora (regular and Atomic variants)
Ubuntu/Debian (and derivatives)
openSUSE/SLES

Installation

Quick Install

# Download and extract
tar -xzf corsair-ai300-fan-controller-bash.tar.gz
cd corsair-ai300-fan-controller-bash

# Run the installer (auto-detects your OS and installs dependencies)
sudo ./install_fan_controller_bash.sh

# Start the service
sudo systemctl start fan-controller-bash.service

That's it! The installer will:

Detect your Linux distribution
Install lm-sensors using your package manager
Configure sensors automatically
Install the fan controller script
Set up the systemd service
Enable auto-start on boot

Bazzite/Fedora Atomic Note

On immutable systems (Bazzite), the installer will:

Install lm-sensors via rpm-ostree
Prompt you to reboot
After reboot, run the installer again to complete setup

This is normal for immutable distributions.

Manual Installation

If you prefer to install manually:

# Install lm-sensors for your distro
# Arch:
sudo pacman -S lm_sensors

# Fedora:
sudo dnf install lm_sensors

# Ubuntu/Debian:
sudo apt install lm-sensors

# Bazzite:
rpm-ostree install lm_sensors && systemctl reboot

# Configure sensors
sudo sensors-detect --auto

# Install the script and service
sudo cp temp_fan_controller.sh /usr/local/bin/
sudo chmod +x /usr/local/bin/temp_fan_controller.sh
sudo cp fan-controller-bash.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable fan-controller-bash.service
sudo systemctl start fan-controller-bash.service

Usage

Start/Stop the Service

# Start
sudo systemctl start fan-controller-bash.service

# Stop
sudo systemctl stop fan-controller-bash.service

# Restart
sudo systemctl restart fan-controller-bash.service

# Check status
sudo systemctl status fan-controller-bash.service

View Logs

# Follow logs in real-time
sudo journalctl -u fan-controller-bash.service -f

# View last 50 lines
sudo journalctl -u fan-controller-bash.service -n 50

Expected output:

[2026-02-19 10:30:45] === Starting Automatic Fan Controller ===
[2026-02-19 10:30:45] Detecting temperature sensors...
[2026-02-19 10:30:45]   Found: k10temp - temp1_input (Tdie)
[2026-02-19 10:30:45] Detected 1 temperature sensor(s)
[2026-02-19 10:30:45] Detecting fan PWM controls...
[2026-02-19 10:30:45]   Found: it8792 - pwm1
[2026-02-19 10:30:45] Detected 1 fan control(s)
[2026-02-19 10:30:45] Starting monitoring loop...
[2026-02-19 10:30:45] Temperature: 45°C -> Setting fan speed to 30%
[2026-02-19 10:35:22] Temperature: 68°C -> Setting fan speed to 75%

Test Before Installing

Run the script manually to see what it detects:

sudo ./temp_fan_controller.sh

Press Ctrl+C to stop. The script will automatically reset fans to automatic mode.

Enable/Disable Auto-Start

# Enable auto-start on boot
sudo systemctl enable fan-controller-bash.service

# Disable auto-start
sudo systemctl disable fan-controller-bash.service

Configuration

Edit the configuration variables at the top of the script:

sudo nano /usr/local/bin/temp_fan_controller.sh

Default Configuration

# Temperature thresholds (°C)
TEMP_LOW=50         # Below 50°C - minimum fan speed
TEMP_MEDIUM=65      # 50-65°C - medium fan speed
TEMP_HIGH=75        # 65-75°C - high fan speed
TEMP_CRITICAL=85    # Above 85°C - maximum fan speed

# Fan speeds (%)
FAN_SPEED_LOW=30        # 30% fan speed
FAN_SPEED_MEDIUM=50     # 50% fan speed
FAN_SPEED_HIGH=75       # 75% fan speed
FAN_SPEED_CRITICAL=100  # 100% fan speed

# Check interval (seconds)
CHECK_INTERVAL=5    # Check every 5 seconds

Temperature/Speed Curve

Temperature	Fan Speed	Use Case
< 50°C	30%	Idle/light tasks - quiet operation
50-65°C	50%	Normal use - balanced
65-75°C	75%	Heavy workload - prioritize cooling
> 85°C	100%	Critical - maximum cooling

Example Configurations

Quiet Profile (prioritize silence):

TEMP_LOW=55
TEMP_MEDIUM=70
TEMP_HIGH=80
TEMP_CRITICAL=90

FAN_SPEED_LOW=25
FAN_SPEED_MEDIUM=40
FAN_SPEED_HIGH=65
FAN_SPEED_CRITICAL=100

Aggressive Profile (prioritize cooling):

TEMP_LOW=45
TEMP_MEDIUM=60
TEMP_HIGH=70
TEMP_CRITICAL=80

FAN_SPEED_LOW=40
FAN_SPEED_MEDIUM=60
FAN_SPEED_HIGH=85
FAN_SPEED_CRITICAL=100

After editing, restart the service:

sudo systemctl restart fan-controller-bash.service

Troubleshooting

Check Available Sensors

sensors

Expected output:

k10temp-pci-00c3
Adapter: PCI adapter
Tctl:         +45.0°C
Tdie:         +45.0°C

No Sensors Detected

Run sensor detection:

sudo sensors-detect
# Answer YES to all questions
sudo systemctl restart lm_sensors
sensors

Check Temperature Files

find /sys/class/hwmon -name "temp*_input"

You should see files like:

/sys/class/hwmon/hwmon2/temp1_input
/sys/class/hwmon/hwmon2/temp2_input

Check PWM Fan Controls

find /sys/class/hwmon -name "pwm[0-9]" -not -name "*_enable"

You should see files like:

/sys/class/hwmon/hwmon3/pwm1
/sys/class/hwmon/hwmon3/pwm2

No PWM Controls Found

If no PWM controls are found, your system may:

Use BIOS-only fan control
Require specific kernel modules
Use a different control interface

Try loading common fan control modules:

sudo modprobe it87
sudo modprobe nct6775

Then check again:

find /sys/class/hwmon -name "pwm*"

Service Fails to Start

Check the service logs:

sudo journalctl -u fan-controller-bash.service -n 50

Common issues:

lm-sensors not installed → Run the installer again
No sensors detected → Run sudo sensors-detect
No PWM controls → Your hardware may not support software fan control
Permission denied → Make sure the service is running as root (it should be automatically)

Test What the Script Detects

Run manually to see detailed detection output:

sudo ./temp_fan_controller.sh

This shows exactly which sensors and fan controls were detected.

How It Works

Detection Phase

Scans /sys/class/hwmon/hwmon*/ directories
Finds all temp*_input files (temperature sensors)
Finds all pwm* files with corresponding pwm*_enable files
Validates write permissions

Monitoring Loop

Reads all temperature sensors every 5 seconds
Determines the highest temperature
Calculates appropriate fan speed based on thresholds
Only updates PWM when speed needs to change (reduces unnecessary writes)

Fan Control

Sets pwm*_enable to 1 (manual/PWM mode)
Writes PWM value (0-255) to pwm* file
PWM percentage = (value / 255) × 100

Cleanup on Exit

Catches SIGINT (Ctrl+C) and SIGTERM signals
Resets pwm*_enable to 2 (automatic mode)
Returns fan control to system/BIOS

Performance Impact

Metric	Impact
Memory Usage	2-5 MB
CPU Usage	<0.1% (sleeps 95% of the time)
Disk I/O	Minimal (only sysfs reads)
Network	None

This is negligible even on low-power systems.

Why Bash Over Python?

Feature	Bash	Python
Memory	2-5 MB	10-15 MB
Startup	Instant	~100ms
Dependencies	None (built-in)	Python 3 interpreter
Best For	System daemons	Development/complex logic

For a simple monitoring daemon, bash is more appropriate and efficient.

Security

The systemd service includes hardening options:

NoNewPrivileges=true - Prevents privilege escalation
PrivateTmp=true - Isolated /tmp directory

The script:

Only reads from /sys/class/hwmon/
Only writes to PWM control files
No network access
No arbitrary file system access

🗑️ Uninstallation

# Stop and disable service
sudo systemctl stop fan-controller-bash.service
sudo systemctl disable fan-controller-bash.service

# Remove files
sudo rm /etc/systemd/system/fan-controller-bash.service
sudo rm /usr/local/bin/temp_fan_controller.sh

# Reload systemd
sudo systemctl daemon-reload

# Optionally remove lm-sensors (Arch example)
sudo pacman -Rs lm_sensors

Contributing

Contributions are welcome! Here are some ideas:

Individual fan control (different speeds per fan)
Hysteresis to prevent rapid speed changes
Configuration file support
Web interface for monitoring
Email/notification alerts on high temps
Support for more exotic hardware
Better error handling

Feel free to open issues or submit pull requests!

📝 License

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

See https://www.gnu.org/licenses/gpl-3.0.en.html for details.

Credits

Originally created for the Corsair AI Workstation 300 mini PC, but designed to work on any Linux system with standard hwmon PWM fan controls.

Support

If you encounter issues:

Check the Troubleshooting section
Run the script manually with sudo ./temp_fan_controller.sh to see detailed output
Check logs with sudo journalctl -u fan-controller-bash.service -n 50
Open an issue on GitHub with:
- Your distro and kernel version (uname -a)
- Output of sensors
- Output of ls -la /sys/class/hwmon/*/pwm*
- Relevant log snippets

Disclaimer

This software comes with no warranty. While it includes safety features (automatic reset to BIOS control on exit, thermal throttling still active), use at your own risk. Monitor your system temperatures when first using this script to ensure it's working as expected for your hardware.

Made with ❤️ for the Linux community

Name		Name	Last commit message	Last commit date
LICENSE		LICENSE
QUICK_START.md		QUICK_START.md
README.md		README.md
fan-controller-bash.service		fan-controller-bash.service
install_fan_controller_bash.sh		install_fan_controller_bash.sh
temp_fan_controller.sh		temp_fan_controller.sh

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