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9 <productname>systemd</productname>
12 <contrib>Developer</contrib>
13 <firstname>Greg</firstname>
14 <surname>Kroah-Hartmann</surname>
15 <email>greg@kroah.com</email>
18 <contrib>Developer</contrib>
19 <firstname>Kay</firstname>
20 <surname>Sievers</surname>
21 <email>kay@vrfy.org</email>
27 <refentrytitle>udev</refentrytitle>
28 <manvolnum>7</manvolnum>
32 <refname>udev</refname>
33 <refpurpose>Dynamic device management</refpurpose>
36 <refsect1><title>Description</title>
37 <para>udev supplies the system software with device events, manages permissions
38 of device nodes and may create additional symlinks in the <filename>/dev</filename>
39 directory, or renames network interfaces. The kernel usually just assigns unpredictable
40 device names based on the order of discovery. Meaningful symlinks or network device
41 names provide a way to reliably identify devices based on their properties or
42 current configuration.</para>
44 <para>The udev daemon, <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle>
45 <manvolnum>8</manvolnum></citerefentry>, receives device uevents directly from
46 the kernel whenever a device is added or removed from the system, or it changes its
47 state. When udev receives a device event, it matches its configured set of rules
48 against various device attributes to identify the device. Rules that match may
49 provide additional device information to be stored in the udev database or
50 to be used to create meaningful symlink names.</para>
52 <para>All device information udev processes is stored in the udev database and
53 sent out to possible event subscribers. Access to all stored data and the event
54 sources is provided by the library libudev.</para>
57 <refsect1><title>Rules Files</title>
58 <para>The udev rules are read from the files located in the
59 system rules directory <filename>/usr/lib/udev/rules.d</filename>,
60 the volatile runtime directory <filename>/run/udev/rules.d</filename>
61 and the local administration directory <filename>/etc/udev/rules.d</filename>.
62 All rules files are collectively sorted and processed in lexical order,
63 regardless of the directories in which they live. However, files with
64 identical filenames replace each other. Files in <filename>/etc</filename>
65 have the highest priority, files in <filename>/run</filename> take precedence
66 over files with the same name in <filename>/usr/lib</filename>. This can be
67 used to override a system-supplied rules file with a local file if needed;
68 a symlink in <filename>/etc</filename> with the same name as a rules file in
69 <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
70 disables the rules file entirely. Rule files must have the extension
71 <filename>.rules</filename>; other extensions are ignored.</para>
73 <para>Every line in the rules file contains at least one key-value pair.
74 Except for empty lines or lines beginning with <literal>#</literal>, which are ignored.
75 There are two kinds of keys: match and assignment.
76 If all match keys match against their values, the rule gets applied and the
77 assignment keys get the specified values assigned.</para>
79 <para>A matching rule may rename a network interface, add symlinks
80 pointing to the device node, or run a specified program as part of
81 the event handling.</para>
83 <para>A rule consists of a comma-separated list of one or more key-value pairs.
84 Each key has a distinct operation, depending on the used operator. Valid
88 <term><literal>==</literal></term>
90 <para>Compare for equality.</para>
95 <term><literal>!=</literal></term>
97 <para>Compare for inequality.</para>
102 <term><literal>=</literal></term>
104 <para>Assign a value to a key. Keys that represent a list are reset
105 and only this single value is assigned.</para>
110 <term><literal>+=</literal></term>
112 <para>Add the value to a key that holds a list of entries.</para>
117 <term><literal>:=</literal></term>
119 <para>Assign a value to a key finally; disallow any later changes.</para>
124 <para>The following key names can be used to match against device properties.
125 Some of the keys also match against properties of the parent devices in sysfs,
126 not only the device that has generated the event. If multiple keys that match
127 a parent device are specified in a single rule, all these keys must match at
128 one and the same parent device.</para>
129 <variablelist class='udev-directives'>
131 <term><varname>ACTION</varname></term>
133 <para>Match the name of the event action.</para>
138 <term><varname>DEVPATH</varname></term>
140 <para>Match the devpath of the event device.</para>
145 <term><varname>KERNEL</varname></term>
147 <para>Match the name of the event device.</para>
152 <term><varname>NAME</varname></term>
154 <para>Match the name of a network interface. It can be used once the
155 NAME key has been set in one of the preceding rules.</para>
160 <term><varname>SYMLINK</varname></term>
162 <para>Match the name of a symlink targeting the node. It can
163 be used once a SYMLINK key has been set in one of the preceding
164 rules. There may be multiple symlinks; only one needs to match.
170 <term><varname>SUBSYSTEM</varname></term>
172 <para>Match the subsystem of the event device.</para>
176 <term><varname>DRIVER</varname></term>
178 <para>Match the driver name of the event device. Only set this key for devices
179 which are bound to a driver at the time the event is generated.</para>
183 <term><varname>ATTR{<replaceable>filename</replaceable>}</varname></term>
185 <para>Match sysfs attribute values of the event device. Trailing
186 whitespace in the attribute values is ignored unless the specified match
187 value itself contains trailing whitespace.
193 <term><varname>KERNELS</varname></term>
195 <para>Search the devpath upwards for a matching device name.</para>
200 <term><varname>SUBSYSTEMS</varname></term>
202 <para>Search the devpath upwards for a matching device subsystem name.</para>
207 <term><varname>DRIVERS</varname></term>
209 <para>Search the devpath upwards for a matching device driver name.</para>
214 <term><varname>ATTRS{<replaceable>filename</replaceable>}</varname></term>
216 <para>Search the devpath upwards for a device with matching sysfs attribute values.
217 If multiple <varname>ATTRS</varname> matches are specified, all of them
218 must match on the same device. Trailing whitespace in the attribute values is ignored
219 unless the specified match value itself contains trailing whitespace.</para>
224 <term><varname>TAGS</varname></term>
226 <para>Search the devpath upwards for a device with matching tag.</para>
231 <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
233 <para>Match against a device property value.</para>
238 <term><varname>TAG</varname></term>
240 <para>Match against a device tag.</para>
245 <term><varname>TEST{<replaceable>octal mode mask</replaceable>}</varname></term>
247 <para>Test the existence of a file. An octal mode mask can be specified
253 <term><varname>PROGRAM</varname></term>
255 <para>Execute a program to determine whether there
256 is a match; the key is true if the program returns
257 successfully. The device properties are made available to the
258 executed program in the environment. The program's standard ouput
259 is available in the <varname>RESULT</varname> key.</para>
260 <para>This can only be used for very short-running foreground tasks. For details,
261 see <varname>RUN</varname>.</para>
266 <term><varname>RESULT</varname></term>
268 <para>Match the returned string of the last <varname>PROGRAM</varname> call.
269 This key can be used in the same or in any later rule after a
270 <varname>PROGRAM</varname> call.</para>
275 <para>Most of the fields support shell glob pattern matching. The following
276 pattern characters are supported:</para>
279 <term><literal>*</literal></term>
281 <para>Matches zero or more characters.</para>
285 <term><literal>?</literal></term>
287 <para>Matches any single character.</para>
291 <term><literal>[]</literal></term>
293 <para>Matches any single character specified within the brackets. For
294 example, the pattern string <literal>tty[SR]</literal>
295 would match either <literal>ttyS</literal> or <literal>ttyR</literal>.
296 Ranges are also supported via the <literal>-</literal> character.
297 For example, to match on the range of all digits, the pattern
298 <literal>[0-9]</literal> could be used. If the first character
299 following the <literal>[</literal> is a <literal>!</literal>,
300 any characters not enclosed are matched.</para>
305 <para>The following keys can get values assigned:</para>
306 <variablelist class='udev-directives'>
308 <term><varname>NAME</varname></term>
310 <para>The name to use for a network interface. The name of a device node
311 cannot be changed by udev, only additional symlinks can be created.</para>
316 <term><varname>SYMLINK</varname></term>
318 <para>The name of a symlink targeting the node. Every matching rule adds
319 this value to the list of symlinks to be created.</para>
320 <para>The set of characters to name a symlink is limited. Allowed
321 characters are <literal>0-9A-Za-z#+-.:=@_/</literal>, valid UTF-8 character
322 sequences, and <literal>\x00</literal> hex encoding. All other
323 characters are replaced by a <literal>_</literal> character.</para>
324 <para>Multiple symlinks may be specified by separating the names by the
325 space character. In case multiple devices claim the same name, the link
326 always points to the device with the highest link_priority. If the current
327 device goes away, the links are re-evaluated and the device with the
328 next highest link_priority becomes the owner of the link. If no
329 link_priority is specified, the order of the devices (and which one of
330 them owns the link) is undefined.</para>
331 <para>Symlink names must never conflict with the kernel's default device
332 node names, as that would result in unpredictable behavior.
338 <term><varname>OWNER</varname>, <varname>GROUP</varname>, <varname>MODE</varname></term>
340 <para>The permissions for the device node. Every specified value overrides
341 the compiled-in default value.</para>
346 <term><varname>SECLABEL{<replaceable>module</replaceable>}</varname></term>
348 <para>Applies the specified Linux Security Module label to the device node.</para>
353 <term><varname>ATTR{<replaceable>key</replaceable>}</varname></term>
355 <para>The value that should be written to a sysfs attribute of the
361 <term><varname>ENV{<replaceable>key</replaceable>}</varname></term>
363 <para>Set a device property value. Property names with a leading <literal>.</literal>
364 are neither stored in the database nor exported to events or
365 external tools (run by, for example, the <varname>PROGRAM</varname>
371 <term><varname>TAG</varname></term>
373 <para>Attach a tag to a device. This is used to filter events for users
374 of libudev's monitor functionality, or to enumerate a group of tagged
375 devices. The implementation can only work efficiently if only a few
376 tags are attached to a device. It is only meant to be used in
377 contexts with specific device filter requirements, and not as a
378 general-purpose flag. Excessive use might result in inefficient event
384 <term><varname>RUN{<replaceable>type</replaceable>}</varname></term>
386 <para>Add a program to the list of programs to be executed after
387 processing all the rules for a specific event, depending on
388 <literal>type</literal>:</para>
391 <term><literal>program</literal></term>
393 <para>Execute an external program specified as the assigned
394 value. If no absolute path is given, the program is expected
395 to live in <filename>/usr/lib/udev</filename>; otherwise, the
396 absolute path must be specified.</para>
397 <para>This is the default if no <replaceable>type</replaceable>
402 <term><literal>builtin</literal></term>
404 <para>As <varname>program</varname>, but use one of the
405 built-in programs rather than an external one.</para>
409 <para>The program name and following arguments are separated by spaces.
410 Single quotes can be used to specify arguments with spaces.</para>
411 <para>This can only be used for very short-running foreground tasks. Running an
412 event process for a long period of time may block all further events for
413 this or a dependent device.</para>
414 <para>Starting daemons or other long-running processes is not appropriate
415 for udev; the forked processes, detached or not, will be unconditionally
416 killed after the event handling has finished.</para>
421 <term><varname>LABEL</varname></term>
423 <para>A named label to which a <varname>GOTO</varname> may jump.</para>
428 <term><varname>GOTO</varname></term>
430 <para>Jumps to the next <varname>LABEL</varname> with a matching name.</para>
435 <term><varname>IMPORT{<replaceable>type</replaceable>}</varname></term>
437 <para>Import a set of variables as device properties,
438 depending on <literal>type</literal>:</para>
441 <term><literal>program</literal></term>
443 <para>Execute an external program specified as the assigned value and
444 import its output, which must be in environment key
445 format. Path specification, command/argument separation,
446 and quoting work like in <varname>RUN</varname>.</para>
450 <term><literal>builtin</literal></term>
452 <para>Similar to <literal>program</literal>, but use one of the
453 built-in programs rather than an external one.</para>
457 <term><literal>file</literal></term>
459 <para>Import a text file specified as the assigned value, the content
460 of which must be in environment key format.</para>
464 <term><literal>db</literal></term>
466 <para>Import a single property specified as the assigned value from the
467 current device database. This works only if the database is already populated
468 by an earlier event.</para>
472 <term><literal>cmdline</literal></term>
474 <para>Import a single property from the kernel command line. For simple flags
475 the value of the property is set to <literal>1</literal>.</para>
479 <term><literal>parent</literal></term>
481 <para>Import the stored keys from the parent device by reading
482 the database entry of the parent device. The value assigned to
483 <option>IMPORT{parent}</option> is used as a filter of key names
484 to import (with the same shell glob pattern matching used for
489 <para>This can only be used for very short-running foreground tasks. For details
490 see <option>RUN</option>.</para>
495 <term><varname>WAIT_FOR</varname></term>
497 <para>Wait for a file to become available or until a timeout of
498 10 seconds expires. The path is relative to the sysfs device;
499 if no path is specified, this waits for an attribute to appear.</para>
504 <term><varname>OPTIONS</varname></term>
506 <para>Rule and device options:</para>
507 <variablelist class='udev-directives'>
509 <term><option>link_priority=<replaceable>value</replaceable></option></term>
511 <para>Specify the priority of the created symlinks. Devices with higher
512 priorities overwrite existing symlinks of other devices. The default is 0.</para>
516 <term><option>event_timeout=</option></term>
518 <para>Number of seconds an event waits for operations to finish before
519 giving up and terminating itself.</para>
523 <term><option>string_escape=<replaceable>none|replace</replaceable></option></term>
525 <para>Usually control and other possibly unsafe characters are replaced
526 in strings used for device naming. The mode of replacement can be specified
527 with this option.</para>
531 <term><option>static_node=</option></term>
533 <para>Apply the permissions specified in this rule to the
534 static device node with the specified name. Also, for every
535 tag specified in this rule, create a symlink
537 <filename>/run/udev/static_node-tags/<replaceable>tag</replaceable></filename>
538 pointing at the static device node with the specified name.
539 Static device node creation is performed by systemd-tmpfiles
540 before systemd-udevd is started. The static nodes might not
541 have a corresponding kernel device; they are used to trigger
542 automatic kernel module loading when they are accessed.</para>
546 <term><option>watch</option></term>
548 <para>Watch the device node with inotify; when the node is
549 closed after being opened for writing, a change uevent is
554 <term><option>nowatch</option></term>
556 <para>Disable the watching of a device node with inotify.</para>
564 <para>The <varname>NAME</varname>, <varname>SYMLINK</varname>,
565 <varname>PROGRAM</varname>, <varname>OWNER</varname>,
566 <varname>GROUP</varname>, <varname>MODE</varname>, and
567 <varname>RUN</varname> fields support simple string substitutions.
568 The <varname>RUN</varname> substitutions are performed after all rules
569 have been processed, right before the program is executed, allowing for
570 the use of device properties set by earlier matching rules. For all other
571 fields, substitutions are performed while the individual rule is being
572 processed. The available substitutions are:</para>
573 <variablelist class='udev-directives'>
575 <term><option>$kernel</option>, <option>%k</option></term>
577 <para>The kernel name for this device.</para>
582 <term><option>$number</option>, <option>%n</option></term>
584 <para>The kernel number for this device. For example,
585 <literal>sda3</literal> has kernel number <literal>3</literal>.
591 <term><option>$devpath</option>, <option>%p</option></term>
593 <para>The devpath of the device.</para>
598 <term><option>$id</option>, <option>%b</option></term>
600 <para>The name of the device matched while searching the devpath
601 upwards for <option>SUBSYSTEMS</option>, <option>KERNELS</option>,
602 <option>DRIVERS</option>, and <option>ATTRS</option>.
608 <term><option>$driver</option></term>
610 <para>The driver name of the device matched while searching the
611 devpath upwards for <option>SUBSYSTEMS</option>,
612 <option>KERNELS</option>, <option>DRIVERS</option>, and
613 <option>ATTRS</option>.
619 <term><option>$attr{<replaceable>file</replaceable>}</option>, <option>%s{<replaceable>file</replaceable>}</option></term>
621 <para>The value of a sysfs attribute found at the device where
622 all keys of the rule have matched. If the matching device does not
623 have such an attribute, and a previous <option>KERNELS</option>,
624 <option>SUBSYSTEMS</option>, <option>DRIVERS</option>, or
625 <option>ATTRS</option> test selected a parent device, then the
626 attribute from that parent device is used.
628 <para>If the attribute is a symlink, the last element of the
629 symlink target is returned as the value.
635 <term><option>$env{<replaceable>key</replaceable>}</option>, <option>%E{<replaceable>key</replaceable>}</option></term>
637 <para>A device property value.</para>
642 <term><option>$major</option>, <option>%M</option></term>
644 <para>The kernel major number for the device.</para>
649 <term><option>$minor</option>, <option>%m</option></term>
651 <para>The kernel minor number for the device.</para>
656 <term><option>$result</option>, <option>%c</option></term>
658 <para>The string returned by the external program requested with
659 <varname>PROGRAM</varname>.
660 A single part of the string, separated by a space character, may be selected
661 by specifying the part number as an attribute: <literal>%c{N}</literal>.
662 If the number is followed by the <literal>+</literal> character, this part plus all remaining parts
663 of the result string are substituted: <literal>%c{N+}</literal>.</para>
668 <term><option>$parent</option>, <option>%P</option></term>
670 <para>The node name of the parent device.</para>
675 <term><option>$name</option></term>
677 <para>The current name of the device. If not changed by a rule, it is the
678 name of the kernel device.</para>
683 <term><option>$links</option></term>
685 <para>A space-separated list of the current symlinks. The value is
686 only set during a remove event or if an earlier rule assigned a value.</para>
691 <term><option>$root</option>, <option>%r</option></term>
693 <para>The udev_root value.</para>
698 <term><option>$sys</option>, <option>%S</option></term>
700 <para>The sysfs mount point.</para>
705 <term><option>$devnode</option>, <option>%N</option></term>
707 <para>The name of the device node.</para>
712 <term><option>%%</option></term>
714 <para>The <literal>%</literal> character itself.</para>
719 <term><option>$$</option></term>
721 <para>The <literal>$</literal> character itself.</para>
727 <refsect1><title>Hardware Database Files</title>
728 <para>The hwdb files are read from the files located in the
729 system hwdb directory <filename>/usr/lib/udev/hwdb.d</filename>,
730 the volatile runtime directory <filename>/run/udev/hwdb.d</filename>
731 and the local administration directory <filename>/etc/udev/hwdb.d</filename>.
732 All hwdb files are collectively sorted and processed in lexical order,
733 regardless of the directories in which they live. However, files with
734 identical filenames replace each other. Files in <filename>/etc</filename>
735 have the highest priority, files in <filename>/run</filename> take precedence
736 over files with the same name in <filename>/usr/lib</filename>. This can be
737 used to override a system-supplied hwdb file with a local file if needed;
738 a symlink in <filename>/etc</filename> with the same name as a hwdb file in
739 <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
740 disables the hwdb file entirely. hwdb files must have the extension
741 <filename>.hwdb</filename>; other extensions are ignored.</para>
743 <para>The hwdb file contains data records consisting of matches and
744 associated key-value pairs. Every record in the hwdb starts with one or
745 more match string, specifying a shell glob to compare the database
746 lookup string against. Multiple match lines are specified in additional
747 consecutive lines. Every match line is compared indivdually, they are
748 combined by OR. Every match line must start at the first character of
751 <para>The match lines are followed by one or more key-value pair lines, which
752 are recognized by a leading space character. The key name and value are separated
753 by <literal>=</literal>. An empty line signifies the end
754 of a record. Lines beginning with <literal>#</literal> are ignored.</para>
756 <para>The content of all hwdb files is read by
757 <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
758 and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>.
759 During runtime only the binary database is used.</para>
762 <refsect1><title>Network Link Configuration</title>
763 <para>Network link configuration is performed by the <literal>net_setup_link</literal>
766 <para>The link files are read from the files located in the
767 system network directory <filename>/usr/lib/systemd/network</filename>,
768 the volatile runtime network directory <filename>/run/systemd/network</filename>
769 and the local administration network directory <filename>/etc/systemd/network</filename>.
770 Link files must have the extension <filename>.link</filename>; other extensions are ignored.
771 All link files are collectively sorted and processed in lexical order,
772 regardless of the directories in which they live. However, files with
773 identical filenames replace each other. Files in <filename>/etc</filename>
774 have the highest priority, files in <filename>/run</filename> take precedence
775 over files with the same name in <filename>/usr/lib</filename>. This can be
776 used to override a system-supplied link file with a local file if needed;
777 a symlink in <filename>/etc</filename> with the same name as a link file in
778 <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
779 disables the link file entirely.</para>
781 <para>The link file contains a <literal>[Match]</literal> section, which
782 determines if a given link file may be applied to a given device; and a
783 <literal>[Link]</literal> section specifying how the device should be
784 configured. The first (in lexical order) of the link files that matches
785 a given device is applied.</para>
787 <para>A link file is said to match a device if each of the entries in the
788 <literal>[Match]</literal> section matches, or if the section is empty.
789 The following keys are accepted:</para>
791 <variablelist class='network-directives'>
793 <term><varname>MACAddress=</varname></term>
795 <para>The hardware address.
800 <term><varname>Path=</varname></term>
802 <para>The persistent path, as exposed by the udev property <literal>ID_PATH</literal>.
803 May contain shell style globs.</para>
807 <term><varname>Driver=</varname></term>
809 <para>The driver currently bound to the device, as exposed by the
810 udev property <literal>DRIVER</literal> of its parent device.</para>
814 <term><varname>Type=</varname></term>
816 <para>The device type, as exposed by the udev property <literal>DEVTYPE</literal>.</para>
820 <term><varname>Host=</varname></term>
822 <para>Matches against the hostname or machine ID of the
823 host. See <literal>ConditionHost=</literal> in
824 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
829 <term><varname>Virtualization=</varname></term>
831 <para>Checks whether the system is executed in a virtualized
832 environment and optionally test whether it is a specific
833 implementation. See <literal>ConditionVirtualization=</literal> in
834 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
839 <term><varname>KernelCommandLine=</varname></term>
841 <para>Checks whether a specific kernel command line option is
842 set (or if prefixed with the exclamation mark unset). See
843 <literal>ConditionKernelCommandLine=</literal> in
844 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
849 <term><varname>Architecture=</varname></term>
851 <para>Checks whether the system is running on a specific
852 architecture. See <literal>ConditionArchitecture=</literal> in
853 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
859 <para>The <literal>[Link]</literal> section accepts the following keys:</para>
861 <variablelist class='network-directives'>
863 <term><varname>Description=</varname></term>
865 <para>A description of the device.</para>
869 <term><varname>Alias=</varname></term>
871 <para>The <literal>ifalias</literal> is set to this value.</para>
875 <term><varname>MACAddressPolicy=</varname></term>
877 <para>The policy by which the MAC address should be set. The
878 available policies are:
882 <term><literal>persistent</literal></term>
884 <para>If the hardware has a persistent MAC address, as most
885 hardware should, and this is used by the kernel, nothing is
886 done. Otherwise, a new MAC address is generated which is
887 guaranteed to be the same on every boot for the given
888 machine and the given device, but which is otherwise random.
893 <term><literal>random</literal></term>
895 <para>If the kernel is using a random MAC address, nothing is
896 done. Otherwise, a new address is randomly generated each
897 time the device appears, typically at boot.
905 <term><varname>MACAddress=</varname></term>
907 <para>The MAC address to use, if no <literal>MACAddressPolicy=</literal>
913 <term><varname>NamePolicy=</varname></term>
915 <para>An ordered, space-separated list of policies by which the
916 interface name should be set. <literal>NamePolicy</literal> may
917 be disabled by specifying <literal>net.ifnames=0</literal> on the
918 kernel commandline. Each of the policies may fail, and the first
919 successful one is used. The name is not set directly, but
920 is exported to udev as the property <literal>ID_NET_NAME</literal>,
921 which is, by default, used by a udev rule to set
922 <literal>NAME</literal>. The available policies are:
926 <term><literal>database</literal></term>
928 <para>The name is set based on entries in the Hardware
929 Database with the key
930 <literal>ID_NET_NAME_FROM_DATABASE</literal>.
935 <term><literal>onboard</literal></term>
937 <para>The name is set based on information given by the
938 firmware for on-board devices, as exported by the udev
939 property <literal>ID_NET_NAME_ONBOARD</literal>.
944 <term><literal>slot</literal></term>
946 <para>The name is set based on information given by the
947 firmware for hot-plug devices, as exported by the udev
948 property <literal>ID_NET_NAME_SLOT</literal>.
953 <term><literal>path</literal></term>
955 <para>The name is set based on the device's physical location,
956 as exported by the udev property
957 <literal>ID_NET_NAME_PATH</literal>.
962 <term><literal>mac</literal></term>
964 <para>The name is set based on the device's persistent MAC
965 address, as exported by the udev property
966 <literal>ID_NET_NAME_MAC</literal>.
974 <term><varname>Name=</varname></term>
976 <para>The interface name to use in case all the policies specified
977 in <varname>NamePolicy=</varname> fail, or in case
978 <varname>NamePolicy=</varname> is missing or disabled.
983 <term><varname>MTU=</varname></term>
985 <para>The MTU to set for the device.</para>
989 <term><varname>SpeedMBytes=</varname></term>
991 <para>The speed to set for the device.</para>
995 <term><varname>Duplex=</varname></term>
997 <para>The duplex mode to set for the device. The accepted values
998 are <literal>half</literal> and <literal>full</literal>.
1003 <term><varname>WakeOnLan=</varname></term>
1005 <para>The Wake-on-LAN policy to set for the device. The supported
1010 <term><literal>phy</literal></term>
1012 <para>Wake on PHY activity.</para>
1016 <term><literal>magic</literal></term>
1018 <para>Wake on receipt of a magic packet.</para>
1022 <term><literal>off</literal></term>
1024 <para>Never wake.</para>
1034 <title>See Also</title>
1037 <refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum>
1040 <refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum>