knowledge/technology/linux/udev.md
2025-06-26 08:17:03 +02:00

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---
obj: application
arch-wiki: https://wiki.archlinux.org/title/Udev
---
# udev
udev is a userspace system that enables the operating system administrator to register userspace handlers for events. The events received by udev's daemon are mainly generated by the (Linux) kernel in response to physical events relating to peripheral devices. As such, udev's main purpose is to act upon peripheral detection and hot-plugging, including actions that return control to the kernel, e.g., loading kernel modules or device firmware. Another component of this detection is adjusting the permissions of the device to be accessible to non-root users and groups.
## Usage
Send control commands or test the device manager.
Usage: `udevadm [--help] [--version] [--debug] COMMAND [COMMAND OPTIONS]`
Commands:
```
info Query sysfs or the udev database
trigger Request events from the kernel
settle Wait for pending udev events
control Control the udev daemon
monitor Listen to kernel and udev events
test Test an event run
test-builtin Test a built-in command
verify Verify udev rules files
wait Wait for device or device symlink
lock Lock a block device
```