diff --git a/man/udev.xml b/man/udev.xml index 3cf3c7f5b..69be5d19c 100644 --- a/man/udev.xml +++ b/man/udev.xml @@ -762,6 +762,43 @@ During runtime only the binary database is used. + Hardware Database Files + 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. + + 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. + + 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 + udevadm8 + 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. + + See Also