1HWDB(7) hwdb HWDB(7)
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6 hwdb - Hardware Database
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9 The hardware database is a key-value store for associating
10 modalias-like keys to udev-properties-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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15 The hwdb files are read from the files located in the system hwdb
16 directory /usr/lib/udev/hwdb.d, the volatile runtime directory
17 /run/udev/hwdb.d and the local administration directory
18 /etc/udev/hwdb.d. All hwdb files are collectively sorted and processed
19 in lexical order, regardless of the directories in which they live.
20 However, files with identical filenames replace each other. Files in
21 /etc have the highest priority, files in /run take precedence over
22 files with the same name in /usr/lib. This can be used to override a
23 system-supplied hwdb file with a local file if needed; a symlink in
24 /etc with the same name as a hwdb file in /usr/lib, pointing to
25 /dev/null, disables the hwdb file entirely. hwdb files must have the
26 extension .hwdb; other extensions are ignored.
27 The hwdb file contains data records consisting of matches and
29 associated key-value pairs. Every record in the hwdb starts with one or
30 more match string, specifying a shell glob to compare the database
31 lookup string against. Multiple match lines are specified in additional
32 consecutive lines. Every match line is compared indivdually, they are
33 combined by OR. Every match line must start at the first character of
34 the line.
35 The match lines are followed by one or more key-value pair lines, which
37 are recognized by a leading space character. The key name and value are
38 separated by "=". An empty line signifies the end of a record. Lines
39 beginning with "#" are ignored.
40 The content of all hwdb files is read by systemd-hwdb(8) and compiled
42 to a binary database located at /etc/udev/hwdb.bin, or alternatively
43 /usr/lib/udev/hwdb.bin if you want ship the compiled database in an
44 immutable image. During runtime only the binary database is used.
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47 systemd-hwdb(8)
48systemd 219 HWDB(7)