1HWDB(7)                              hwdb                              HWDB(7)
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NAME

6       hwdb - Hardware Database
7

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.
26
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       Match patterns consist of literal characters, and shell-style
35       wildcards:
36
37       •   Asterisk "*" matches any number of characters
38
39       •   Question mark "?"  matches a single character
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41       •   Character list "[chars]" matches one of the characters chars listed
42           between "[" and "]". A range may be specified as with a dash as
43           "[first-last]". The match may be inverted with a caret "[^...]".
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45       The match lines are followed by one or more key-value pair lines, which
46       are recognized by a leading space character. The key name and value are
47       separated by "=". An empty line signifies the end of a record. Lines
48       beginning with "#" are ignored.
49
50       In case multiple records match a given lookup string, the key-value
51       pairs from all records are combined. If a key is specified multiple
52       times, the value from the record with the highest priority is used
53       (each key can have only a single value). The priority is higher when
54       the record is in a file that sorts later lexicographically, and in case
55       of records in the same file, later records have higher priority.
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57       The content of all hwdb files is read by systemd-hwdb(8) and compiled
58       to a binary database located at /etc/udev/hwdb.bin, or alternatively
59       /usr/lib/udev/hwdb.bin if you want ship the compiled database in an
60       immutable image. During runtime, only the binary database is used.
61

EXAMPLES

63       Example 1. General syntax of hwdb files
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65           # /usr/lib/udev/hwdb.d/example.hwdb
66           # Comments can be placed before any records. This is a good spot
67           # to describe what that file is used for, what kind of properties
68           # it defines, and the ordering convention.
69
70           # A record with three matches and one property
71           mouse:*:name:*Trackball*:*
72           mouse:*:name:*trackball*:*
73           mouse:*:name:*TrackBall*:*
74            ID_INPUT_TRACKBALL=1
75
76           # The rule above could be also be written in a form that
77           # matches Tb, tb, TB, tB:
78           mouse:*:name:*[tT]rack[bB]all*:*
79            ID_INPUT_TRACKBALL=1
80
81           # A record with a single match and five properties
82           mouse:usb:v046dp4041:name:Logitech MX Master:*
83            MOUSE_DPI=1000@166
84            MOUSE_WHEEL_CLICK_ANGLE=15
85            MOUSE_WHEEL_CLICK_ANGLE_HORIZONTAL=26
86            MOUSE_WHEEL_CLICK_COUNT=24
87            MOUSE_WHEEL_CLICK_COUNT_HORIZONTAL=14
88
89       Example 2. Overriding of properties
90
91           # /usr/lib/udev/hwdb.d/60-keyboard.hwdb
92           evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer*:pn*:*
93            KEYBOARD_KEY_a1=help
94            KEYBOARD_KEY_a2=setup
95            KEYBOARD_KEY_a3=battery
96
97           # Match vendor name "Acer" and any product name starting with "X123"
98           evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer:pnX123*:*
99            KEYBOARD_KEY_a2=wlan
100
101           # /etc/udev/hwdb.d/70-keyboard.hwdb
102           # disable wlan key on all at keyboards
103           evdev:atkbd:*
104            KEYBOARD_KEY_a2=reserved
105            PROPERTY_WITH_SPACES=some string
106
107       If the hwdb consists of those two files, a keyboard with the lookup
108       string "evdev:atkbd:dmi:bvnAcer:bdXXXXX:bd08/05/2010:svnAcer:pnX123"
109       will match all three records, and end up with the following properties:
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111           KEYBOARD_KEY_a1=help
112           KEYBOARD_KEY_a2=reserved
113           KEYBOARD_KEY_a3=battery
114           PROPERTY_WITH_SPACES=some string
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SEE ALSO

117       systemd-hwdb(8)
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121systemd 253                                                            HWDB(7)
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