---
name: "udevd"
section: "8"
platform: "linux"
package: "udev"
version: "215-17+deb8u7"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/systemd-udevd.service"
---

# udevd(8)

Device event managing daemon

Part of [systemd-udevd.service(8)](/systemd-udevd.service/8.md).

## NAME

systemd-udevd.service, systemd-udevd-control.socket, systemd-udevd-kernel.socket, systemd-udevd - Device event managing daemon

## SYNOPSIS

systemd-udevd.service

systemd-udevd-control.socket

systemd-udevd-kernel.socket

**/lib/systemd/systemd-udevd** \[**--daemon**\] \[**--debug**\] \[**--children-max=**\] \[**--exec-delay=**\] \[**--resolve-names=early\|late\|never**\] \[**--version**\] \[**--help**\]

## DESCRIPTION

**systemd-udevd** listens to kernel uevents. For every event, systemd-udevd executes matching instructions specified in udev rules. See [**udev**(7)](/udev/7.md).

The behavior of the running daemon can be changed with **udevadm control**.

## OPTIONS

- **--daemon**

  Detach and run in the background.

- **--debug**

  Print debug messages to standard error.

**--children-max=**

Limit the number of events executed in parallel.

**--exec-delay=**

Delay the execution of *RUN* instructions by the given number of seconds. This option might be useful when debugging system crashes during coldplug caused by loading non-working kernel modules.

**--resolve-names=**

Specify when systemd-udevd should resolve names of users and groups. When set to **early** (the default), names will be resolved when the rules are parsed. When set to **late**, names will be resolved for every event. When set to **never**, names will never be resolved and all devices will be owned by root.

- **--help**

  Print a short help text and exit.

- **--version**

  Print a short version string and exit.

## ENVIRONMENT

*$UDEV\_LOG=*

Set the logging priority.

## KERNEL COMMAND LINE

Parameters starting with "rd." will be read when **systemd-udevd** is used in an initrd.

*udev.log-priority=*, *rd.udev.log-priority=*

Set the logging priority.

*udev.children-max=*, *rd.udev.children-max=*

Limit the number of events executed in parallel.

*udev.exec-delay=*, *rd.udev.exec-delay=*

Delay the execution of *RUN* instructions by the given number of seconds. This option might be useful when debugging system crashes during coldplug caused by loading non-working kernel modules.

*net.ifnames=*

Network interfaces are renamed to give them predictable names when possible. It is enabled by default; specifying 0 disables it.

## CONFIGURATION FILE

udev expects its main configuration file at /etc/udev/udev.conf. It consists of a set of variables allowing the user to override default udev values. All empty lines or lines beginning with '#' are ignored. The following variables can be set:

*udev\_log*

The logging priority. Valid values are the numerical syslog priorities or their textual representations: **err**, **info** and **debug**.

## SEE ALSO

[**udev**(7)](/udev/7.md), [**udevadm**(8)](/udevadm/8.md)