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diff --git a/man/udev.xml b/man/udev.xml index 3cf3c7f5b3..69be5d19c5 100644 --- a/man/udev.xml +++ b/man/udev.xml @@ -762,6 +762,43 @@ During runtime only the binary database is used.</para> </refsect1> + <refsect1><title>Hardware Database Files</title> + <para>The hwdb files are read from the files located in the + system hwdb directory <filename>/usr/lib/udev/hwdb.d</filename>, + the volatile runtime directory <filename>/run/udev/hwdb.d</filename> + and the local administration directory <filename>/etc/udev/hwdb.d</filename>. + 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 <filename>/etc</filename> + have the highest priority, files in <filename>/run</filename> take precedence + over files with the same name in <filename>/usr/lib</filename>. This can be + used to override a system-supplied hwdb file with a local file if needed; + a symlink in <filename>/etc</filename> with the same name as a hwdb file in + <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, + disables the hwdb file entirely. hwdb files must have the extension + <filename>.hwdb</filename>; other extensions are ignored.</para> + + <para>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.</para> + + <para>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 <literal>=</literal>. An empty line signifies the end + of a record. Lines beginning with <literal>#</literal> are ignored.</para> + + <para>The content of all hwdb files is read by + <citerefentry><refentrytitle>udevadm</refentrytitle><manvolnum>8</manvolnum></citerefentry> + and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>, + or alternatively <filename>/usr/lib/udev/hwdb.bin</filename> if you want ship the compiled + database in an immutable image. + During runtime only the binary database is used.</para> + </refsect1> + <refsect1> <title>See Also</title> <para> |