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.TH "HWDB" "7" "" "systemd 219" "hwdb"
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.SH "NAME"
hwdb \- Hardware Database
.SH "DESCRIPTION"
.PP
The hardware database is a key\-value store for associating modalias\-like keys to udev\-properties\-like values\&. It is used primarily by udev to add the relevant properties to matching devices, but it can also be queried directly\&.
.SH "HARDWARE DATABASE FILES"
.PP
The hwdb files are read from the files located in the system hwdb directory
/usr/lib/udev/hwdb\&.d, the volatile runtime directory
/run/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, files in
/run
take precedence over files with the same name in
/usr/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
/usr/lib, pointing to
/dev/null, disables the hwdb file entirely\&. hwdb files must have the extension
\&.hwdb; other extensions are ignored\&.
.PP
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 string, 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 indivdually, they are combined by OR\&. Every match line must start at the first character of the line\&.
.PP
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\&.
.PP
The content of all hwdb files is read by
\fBsystemd-hwdb\fR(8)
and compiled to a binary database located at
/etc/udev/hwdb\&.bin, or alternatively
/usr/lib/udev/hwdb\&.bin
if you want ship the compiled database in an immutable image\&. During runtime only the binary database is used\&.
.SH "SEE ALSO"
.PP
\fBsystemd-hwdb\fR(8)