<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!--
+ SPDX-License-Identifier: LGPL-2.1+
+
+ This file is part of systemd.
+
+ Copyright 2014 Tom Gundersen
+ Copyright 2016 Zbigniew Jędrzejewski-Szmek
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
<refentry id="hwdb" conditional="ENABLE_HWDB">
<refentryinfo>
<title>hwdb</title>
system-supplied hwdb file with a local file if needed;
a symlink in <filename>/etc</filename> with the same name as a hwdb file in
<filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>,
- disables the hwdb file entirely. hwdb files must have the extension
+ disables that hwdb file entirely. hwdb files must have the extension
<filename>.hwdb</filename>; other extensions are ignored.</para>
- <para>The hwdb file contains data records consisting of matches and
- associated key-value pairs. Every record in the hwdb starts with one or
- more match strings, specifying a shell glob to compare the database
- lookup string against. Multiple match lines are specified in additional
- consecutive lines. Every match line is compared individually, and they are
- combined by OR. Every match line must start at the first character of
- the line.</para>
+ <para>Each hwdb file contains data records consisting of matches and associated
+ key-value pairs. Every record in the hwdb starts with one or more match strings,
+ specifying a shell glob to compare the lookup string against. Multiple match lines
+ are specified in consecutive lines. Every match line is compared individually, and
+ they are combined by OR. Every match line must start at the first character of the
+ line.</para>
+
+ <para>The match lines are followed by one or more key-value pair lines, which are
+ recognized by a leading space character. The key name and value are separated by
+ <literal>=</literal>. An empty line signifies the end of a record. Lines beginning
+ with <literal>#</literal> are ignored.</para>
- <para>The match lines are followed by one or more key-value pair lines, which
- are recognized by a leading space character. The key name and value are separated
- by <literal>=</literal>. An empty line signifies the end
- of a record. Lines beginning with <literal>#</literal> are ignored.</para>
+ <para>In case multiple records match a given lookup string, the key-value pairs
+ from all records are combined. If a key is specified multiple times, the value
+ from the record with the highest priority is used (each key can have only a single
+ value). The priority is higher when the record is in a file that sorts later
+ lexicographically, and in case of records in the same file, later records have
+ higher priority.</para>
<para>The content of all hwdb files is read by
<citerefentry><refentrytitle>systemd-hwdb</refentrytitle><manvolnum>8</manvolnum></citerefentry>
and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>,
- or alternatively <filename>/usr/lib/udev/hwdb.bin</filename> if you want ship the compiled
- database in an immutable image.
- During runtime, only the binary database is used.</para>
+ or alternatively <filename>/usr/lib/udev/hwdb.bin</filename> if you want ship the
+ compiled database in an immutable image. During runtime, only the binary database
+ is used.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Examples</title>
+
+ <example>
+ <title>General syntax of hwdb files</title>
+
+ <programlisting># /usr/lib/udev/hwdb.d/example.hwdb
+# Comments can be placed before any records. This is a good spot
+# to describe what that file is used for, what kind of properties
+# it defines, and the ordering convention.
+
+# A record with three matches and one property
+mouse:*:name:*Trackball*:
+mouse:*:name:*trackball*:
+mouse:*:name:*TrackBall*:
+ ID_INPUT_TRACKBALL=1
+
+# A record with a single match and five properties
+mouse:usb:v046dp4041:name:Logitech MX Master:
+ MOUSE_DPI=1000@166
+ MOUSE_WHEEL_CLICK_ANGLE=15
+ MOUSE_WHEEL_CLICK_ANGLE_HORIZONTAL=26
+ MOUSE_WHEEL_CLICK_COUNT=24
+ MOUSE_WHEEL_CLICK_COUNT_HORIZONTAL=14
+</programlisting>
+ </example>
+
+ <example>
+ <title>Overriding of properties</title>
+
+ <programlisting># /usr/lib/udev/hwdb.d/60-keyboard.hwdb
+evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer*:pn*
+ KEYBOARD_KEY_a1=help
+ KEYBOARD_KEY_a2=setup
+ KEYBOARD_KEY_a3=battery
+
+evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer*:pn123*
+ KEYBOARD_KEY_a2=wlan
+
+# /etc/udev/hwdb.d/70-keyboard.hwdb
+# disable wlan key on all at keyboards
+evdev:atkbd:*
+ KEYBOARD_KEY_a2=reserved</programlisting>
+
+ <para>If the hwdb consists of those two files, a keyboard with the lookup string
+ <literal>evdev:atkbd:dmi:bvnAcer:bdXXXXX:bd08/05/2010:svnAcer:pn123</literal>
+ will match all three records, and end up with the following properties:</para>
+
+ <programlisting>KEYBOARD_KEY_a1=help
+KEYBOARD_KEY_a2=reserved
+KEYBOARD_KEY_a3=battery</programlisting>
+ </example>
</refsect1>
<refsect1>
projects / thirdparty / systemd.git / blobdiff