1HWDB(7)                              hwdb                              HWDB(7)
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NAME

6       hwdb - Hardware Database
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DESCRIPTION

9       The hardware database is a key-value store for associating
10       modalias-like keys to udev-property-like values. It is used primarily
11       by udev to add the relevant properties to matching devices, but it can
12       also be queried directly.
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HARDWARE DATABASE FILES

15       The hwdb files are read from the files located in the system hwdb
16       directory /usr/lib/udev/hwdb.d and the local administration directory
17       /etc/udev/hwdb.d. All hwdb files are collectively sorted and processed
18       in lexical order, regardless of the directories in which they live.
19       However, files with identical filenames replace each other. Files in
20       /etc have the highest priority and take precedence over files with the
21       same name in /usr/lib. This can be used to override a system-supplied
22       hwdb file with a local file if needed; a symlink in /etc with the same
23       name as a hwdb file in /usr/lib, pointing to /dev/null, disables that
24       hwdb file entirely. hwdb files must have the extension .hwdb; other
25       extensions are ignored.
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27       Each hwdb file contains data records consisting of matches and
28       associated key-value pairs. Every record in the hwdb starts with one or
29       more match strings, specifying a shell glob to compare the lookup
30       string against. Multiple match lines are specified in consecutive
31       lines. Every match line is compared individually, and they are combined
32       by OR. Every match line must start at the first character of the line.
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34       The match lines are followed by one or more key-value pair lines, which
35       are recognized by a leading space character. The key name and value are
36       separated by "=". An empty line signifies the end of a record. Lines
37       beginning with "#" are ignored.
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39       In case multiple records match a given lookup string, the key-value
40       pairs from all records are combined. If a key is specified multiple
41       times, the value from the record with the highest priority is used
42       (each key can have only a single value). The priority is higher when
43       the record is in a file that sorts later lexicographically, and in case
44       of records in the same file, later records have higher priority.
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46       The content of all hwdb files is read by systemd-hwdb(8) and compiled
47       to a binary database located at /etc/udev/hwdb.bin, or alternatively
48       /usr/lib/udev/hwdb.bin if you want ship the compiled database in an
49       immutable image. During runtime, only the binary database is used.
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EXAMPLES

52       Example 1. General syntax of hwdb files
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54           # /usr/lib/udev/hwdb.d/example.hwdb
55           # Comments can be placed before any records. This is a good spot
56           # to describe what that file is used for, what kind of properties
57           # it defines, and the ordering convention.
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59           # A record with three matches and one property
60           mouse:*:name:*Trackball*:
61           mouse:*:name:*trackball*:
62           mouse:*:name:*TrackBall*:
63            ID_INPUT_TRACKBALL=1
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65           # A record with a single match and five properties
66           mouse:usb:v046dp4041:name:Logitech MX Master:
67            MOUSE_DPI=1000@166
68            MOUSE_WHEEL_CLICK_ANGLE=15
69            MOUSE_WHEEL_CLICK_ANGLE_HORIZONTAL=26
70            MOUSE_WHEEL_CLICK_COUNT=24
71            MOUSE_WHEEL_CLICK_COUNT_HORIZONTAL=14
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73       Example 2. Overriding of properties
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75           # /usr/lib/udev/hwdb.d/60-keyboard.hwdb
76           evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer*:pn*
77            KEYBOARD_KEY_a1=help
78            KEYBOARD_KEY_a2=setup
79            KEYBOARD_KEY_a3=battery
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81           evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer*:pn123*
82            KEYBOARD_KEY_a2=wlan
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84           # /etc/udev/hwdb.d/70-keyboard.hwdb
85           # disable wlan key on all at keyboards
86           evdev:atkbd:*
87            KEYBOARD_KEY_a2=reserved
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89       If the hwdb consists of those two files, a keyboard with the lookup
90       string "evdev:atkbd:dmi:bvnAcer:bdXXXXX:bd08/05/2010:svnAcer:pn123"
91       will match all three records, and end up with the following properties:
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93           KEYBOARD_KEY_a1=help
94           KEYBOARD_KEY_a2=reserved
95           KEYBOARD_KEY_a3=battery
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SEE ALSO

98       systemd-hwdb(8)
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102systemd 241                                                            HWDB(7)
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