{
    "mode": "man",
    "parameter": "systemd-udevd",
    "section": "8",
    "url": "https://www.chedong.com/phpMan.php/man/systemd-udevd/8/json",
    "generated": "2026-06-02T21:26:37Z",
    "synopsis": "systemd-udevd.service\nsystemd-udevd-control.socket\nsystemd-udevd-kernel.socket\n/lib/systemd/systemd-udevd [--daemon] [--debug] [--children-max=] [--exec-delay=]\n[--event-timeout=] [--resolve-names=early|late|never] [--version]\n[--help]",
    "sections": {
        "NAME": {
            "content": "systemd-udevd.service, systemd-udevd-control.socket, systemd-udevd-kernel.socket, systemd-\nudevd - Device event managing daemon\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "systemd-udevd.service\n\nsystemd-udevd-control.socket\n\nsystemd-udevd-kernel.socket\n\n/lib/systemd/systemd-udevd [--daemon] [--debug] [--children-max=] [--exec-delay=]\n[--event-timeout=] [--resolve-names=early|late|never] [--version]\n[--help]\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "systemd-udevd listens to kernel uevents. For every event, systemd-udevd executes matching\ninstructions specified in udev rules. See udev(7).\n\nThe behavior of the daemon can be configured using udev.conf(5), its command line options,\nenvironment variables, and on the kernel command line, or changed dynamically with udevadm\ncontrol.\n",
            "subsections": []
        },
        "OPTIONS": {
            "content": "",
            "subsections": [
                {
                    "name": "-d --daemon",
                    "content": "Detach and run in the background.\n",
                    "flag": "-d",
                    "long": "--daemon"
                },
                {
                    "name": "-D --debug",
                    "content": "Print debug messages to standard error.\n",
                    "flag": "-D",
                    "long": "--debug"
                },
                {
                    "name": "-c --children-max=",
                    "content": "Limit the number of events executed in parallel.\n",
                    "flag": "-c"
                },
                {
                    "name": "-e --exec-delay=",
                    "content": "Delay the execution of each RUN{program} parameter by the given number of seconds. This\noption might be useful when debugging system crashes during coldplug caused by loading\nnon-working kernel modules.\n",
                    "flag": "-e"
                },
                {
                    "name": "-t --event-timeout=",
                    "content": "Set the number of seconds to wait for events to finish. After this time, the event will\nbe terminated. The default is 180 seconds.\n",
                    "flag": "-t"
                },
                {
                    "name": "-s --timeout-signal=",
                    "content": "Set the signal which systemd-udevd will send to forked off processes after reaching event\ntimeout. The setting can be overridden at boot time with the kernel command line option\nudev.timeoutsignal=. Setting to SIGABRT may be helpful in order to debug worker\ntimeouts. Defaults to SIGKILL. Note that setting the option on the command line overrides\nthe setting from the configuration file.\n",
                    "flag": "-s"
                },
                {
                    "name": "-N --resolve-names=",
                    "content": "Specify when systemd-udevd should resolve names of users and groups. When set to early\n(the default), names will be resolved when the rules are parsed. When set to late, names\nwill be resolved for every event. When set to never, names will never be resolved and all\ndevices will be owned by root.\n",
                    "flag": "-N"
                },
                {
                    "name": "-h --help",
                    "content": "Print a short help text and exit.\n",
                    "flag": "-h",
                    "long": "--help"
                },
                {
                    "name": "--version",
                    "content": "Print a short version string and exit.\n",
                    "long": "--version"
                }
            ]
        },
        "KERNEL COMMAND LINE": {
            "content": "Parameters prefixed with \"rd.\" will be read when systemd-udevd is used in an initrd, those\nwithout will be processed both in the initrd and on the host.\n\nudev.loglevel=, rd.udev.loglevel=\nSet the log level.\n\nudev.childrenmax=, rd.udev.childrenmax=\nLimit the number of events executed in parallel.\n\nudev.execdelay=, rd.udev.execdelay=\nDelay the execution of each RUN{program} parameter by the given number of seconds. This\noption might be useful when debugging system crashes during coldplug caused by loading\nnon-working kernel modules.\n\nudev.eventtimeout=, rd.udev.eventtimeout=\nWait for events to finish up to the given number of seconds. This option might be useful\nif events are terminated due to kernel drivers taking too long to initialize.\n\nudev.timeoutsignal=, rd.udev.timeoutsignal=\nSpecifies a signal that systemd-udevd will send to workers on timeout. Note that kernel\ncommand line option overrides both the setting in the configuration file and the one on\nthe program command line.\n\nudev.blockdevreadonly, rd.udev.blockdevreadonly\nIf specified, mark all physical block devices read-only as they appear. Synthetic block\ndevices (such as loopback block devices or device mapper devices) are left as they are.\nThis is useful to guarantee that the contents of physical block devices remains\nunmodified during runtime, for example to implement fully stateless systems, for testing\nor for recovery situations where corrupted file systems shall not be corrupted further\nthrough accidental modification.\n\nA block device may be marked writable again by issuing the blockdev --setrw command, see\nblockdev(8) for details.\n\nnet.ifnames=\nNetwork interfaces are renamed to give them predictable names when possible. It is\nenabled by default; specifying 0 disables it.\n\nnet.naming-scheme=\nNetwork interfaces are renamed to give them predictable names when possible (unless\nnet.ifnames=0 is specified, see above). With this kernel command line option it is\npossible to pick a specific version of this algorithm and override the default chosen at\ncompilation time. Expects one of the naming scheme identifiers listed in systemd.net-\nnaming-scheme(7), or \"latest\" to select the latest scheme known (to this particular\nversion of systemd-udevd.service).\n\nNote that selecting a specific scheme is not sufficient to fully stabilize interface\nnaming: the naming is generally derived from driver attributes exposed by the kernel. As\nthe kernel is updated, previously missing attributes systemd-udevd.service is checking\nmight appear, which affects older name derivation algorithms, too.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "udev.conf(5), udev(7), udevadm(8)\n\n\n\nsystemd 249                                                                 SYSTEMD-UDEVD.SERVICE(8)",
            "subsections": []
        }
    },
    "summary": "systemd-udevd.service, systemd-udevd-control.socket, systemd-udevd-kernel.socket, systemd- udevd - Device event managing daemon",
    "flags": [
        {
            "flag": "-d",
            "long": "--daemon",
            "arg": null,
            "description": "Detach and run in the background."
        },
        {
            "flag": "-D",
            "long": "--debug",
            "arg": null,
            "description": "Print debug messages to standard error."
        },
        {
            "flag": "-c",
            "long": null,
            "arg": null,
            "description": "Limit the number of events executed in parallel."
        },
        {
            "flag": "-e",
            "long": null,
            "arg": null,
            "description": "Delay the execution of each RUN{program} parameter by the given number of seconds. This option might be useful when debugging system crashes during coldplug caused by loading non-working kernel modules."
        },
        {
            "flag": "-t",
            "long": null,
            "arg": null,
            "description": "Set the number of seconds to wait for events to finish. After this time, the event will be terminated. The default is 180 seconds."
        },
        {
            "flag": "-s",
            "long": null,
            "arg": null,
            "description": "Set the signal which systemd-udevd will send to forked off processes after reaching event timeout. The setting can be overridden at boot time with the kernel command line option udev.timeoutsignal=. Setting to SIGABRT may be helpful in order to debug worker timeouts. Defaults to SIGKILL. Note that setting the option on the command line overrides the setting from the configuration file."
        },
        {
            "flag": "-N",
            "long": null,
            "arg": null,
            "description": "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."
        },
        {
            "flag": "-h",
            "long": "--help",
            "arg": null,
            "description": "Print a short help text and exit."
        },
        {
            "flag": "",
            "long": "--version",
            "arg": null,
            "description": "Print a short version string and exit."
        }
    ],
    "examples": [],
    "see_also": [
        {
            "name": "udev.conf",
            "section": "5",
            "url": "https://www.chedong.com/phpMan.php/man/udev.conf/5/json"
        },
        {
            "name": "udev",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/udev/7/json"
        },
        {
            "name": "udevadm",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/udevadm/8/json"
        },
        {
            "name": "SYSTEMD-UDEVD.SERVICE",
            "section": "8",
            "url": "https://www.chedong.com/phpMan.php/man/SYSTEMD-UDEVD.SERVICE/8/json"
        }
    ]
}