NAME¶
hwdb - Hardware Database
DESCRIPTION¶
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 the
hwdb file entirely. hwdb files must have the extension .hwdb; other extensions
are ignored.
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.
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.
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.
SEE ALSO¶
systemd-hwdb(8)