NAME
hwdb - Hardware DatabaseDESCRIPTION
The hardware database is a key-value store for associating modalias-like keys to udev-property-like values. It is used primarily by udev to add the relevant properties to matching devices, but it can also be queried directly.HARDWARE DATABASE FILES
The hwdb files are read from the files located in the system hwdb directory /lib/udev/hwdb.d and the local administration directory /etc/udev/hwdb.d. All hwdb files are collectively sorted and processed in lexical order, regardless of the directories in which they live. However, files with identical filenames replace each other. Files in /etc/ have the highest priority and take precedence over files with the same name in /lib/. This can be used to override a system-supplied hwdb file with a local file if needed; a symlink in /etc/ with the same name as a hwdb file in /lib/, pointing to /dev/null, disables that hwdb file entirely. hwdb files must have the extension .hwdb; other extensions are ignored. 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. Match patterns consist of literal characters, and shell-style wildcards:•Asterisk "*" matches any
number of characters
•Question mark "?" matches a
single character
•Character list "[
chars]" matches one of the characters chars listed between
"[" and "]". A range may be specified as with a dash as
"[ first-last]". The match may be inverted with a
caret "[^...]".
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 "=". An empty line signifies the end of a record. Lines beginning
with "#" are ignored.
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.
The content of all hwdb files is read by systemd-hwdb(8) and compiled to
a binary database located at /etc/udev/hwdb.bin, or alternatively
/lib/udev/hwdb.bin if you want ship the compiled database in an immutable
image. During runtime, only the binary database is used.
EXAMPLES
Example 1. General syntax of hwdb files# /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 # The rule above could be also be written in a form that # matches Tb, tb, TB, tB: mouse:*:name:*[tT]rack[bB]all*:* 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
# /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 # Match vendor name "Acer" and any product name starting with "X123" evdev:atkbd:dmi:bvn*:bvr*:bd*:svnAcer:pnX123*:* KEYBOARD_KEY_a2=wlan # /etc/udev/hwdb.d/70-keyboard.hwdb # disable wlan key on all at keyboards evdev:atkbd:* KEYBOARD_KEY_a2=reserved PROPERTY_WITH_SPACES=some string
KEYBOARD_KEY_a1=help KEYBOARD_KEY_a2=reserved KEYBOARD_KEY_a3=battery PROPERTY_WITH_SPACES=some string
SEE ALSO
systemd-hwdb(8)systemd 252 |