pyudev: libudev Binding

0.24.4 · active · verified Sat Apr 11

pyudev is an LGPL-licensed, pure Python binding for libudev, the device and hardware management library for Linux. It provides functionality to enumerate devices, query their properties and attributes, and monitor device events, including asynchronous monitoring with various GUI toolkit integrations. The current version is 0.24.4 and it supports CPython 3.9 and newer. It is actively maintained with development on GitHub.

Warnings

gotcha Using a `Device` object in a boolean context (e.g., `if device:`) can yield `False` if the device has no udev properties, even if the device itself is valid. This is due to `Device` inheriting from `Mapping`. Explicitly check for `None` or specific properties instead.
Fix: Avoid `if device:`. Instead, use `if device is not None:` or `if 'PROPERTY_NAME' in device:` if checking for specific data.
deprecated Accessing udev properties directly via `Device` object indexing (e.g., `device['PROPERTY']`) is deprecated since version 0.21.0. The `Device` class no longer behaves like a mapping for properties.
Fix: Use the `Device.get('PROPERTY_NAME', default_value)` method or `device.properties.get('PROPERTY_NAME', default_value)` instead.
gotcha Do not use object identity (`is` operator) to compare `Device` objects (e.g., `device1 is device2`). `pyudev` may create multiple `Device` objects that refer to the same underlying udev device. Compare them by value using `==` or `!=` instead.
Fix: Use `if device1 == device2:` for comparison.
deprecated Methods like `Device.from_sys_path()`, `Device.from_name()`, and `Device.from_device_file()` were deprecated in version 0.18.
Fix: Use the static methods on the `Devices` class, such as `pyudev.Devices.from_sys_path(context, path)`, `pyudev.Devices.from_name(context, subsystem, name)`, or `pyudev.Devices.from_device_file(context, filename)`.

Install

pip install pyudev Install pyudev

Imports

Context
```
from pyudev import Context
```
Device
```
from pyudev import Device
```
Monitor
```
from pyudev import Monitor
```
MonitorObserver
```
from pyudev import MonitorObserver
```
Devices
```
from pyudev import Devices
```

Quickstart

This quickstart initializes a udev context, then demonstrates enumerating all block device partitions and printing their file system labels. It also shows how to set up a monitor to listen for new USB device 'add' events in real-time.

import pyudev

# Create a udev context
context = pyudev.Context()

# Enumerate all block devices that are partitions and print their labels
print('Listing partitions:')
for device in context.list_devices(subsystem='block', DEVTYPE='partition'):
    # Use device.get() for properties, providing a default for safety
    label = device.get('ID_FS_LABEL', 'unlabeled partition')
    print(f"  {device.device_node}: {label}")

# Monitor for new USB devices (example)
print('\nMonitoring for new USB devices (Ctrl+C to stop):')
monitor = pyudev.Monitor.from_netlink(context)
monitor.filter_by(subsystem='usb')
monitor.start() # Start the monitor to receive events

for action, device in monitor:
    if action == 'add':
        print(f"  Added USB device: {device.sys_name} ({device.get('ID_VENDOR_FROM_DATABASE', 'Unknown Vendor')})")

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