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65eb4378 | 1 | <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> |
65eb4378 | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
65eb4378 | 4 | |
3715a071 | 5 | <refentry id="hwdb" conditional="ENABLE_HWDB"> |
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6 | <refentryinfo> |
7 | <title>hwdb</title> | |
8 | <productname>systemd</productname> | |
9 | <authorgroup> | |
10 | <author> | |
11 | <contrib>Developer</contrib> | |
12 | <firstname>Kay</firstname> | |
13 | <surname>Sievers</surname> | |
14 | <email>kay@vrfy.org</email> | |
15 | </author> | |
16 | <author> | |
17 | <contrib>Developer</contrib> | |
18 | <firstname>Tom</firstname> | |
19 | <surname>Gundersen</surname> | |
20 | <email>teg@jklm.no</email> | |
21 | </author> | |
22 | </authorgroup> | |
23 | </refentryinfo> | |
24 | ||
25 | <refmeta> | |
26 | <refentrytitle>hwdb</refentrytitle> | |
27 | <manvolnum>7</manvolnum> | |
28 | </refmeta> | |
29 | ||
30 | <refnamediv> | |
31 | <refname>hwdb</refname> | |
32 | <refpurpose>Hardware Database</refpurpose> | |
33 | </refnamediv> | |
34 | ||
35 | <refsect1><title>Description</title> | |
36 | <para>The hardware database is a key-value store for associating modalias-like keys to | |
a8eaaee7 | 37 | udev-property-like values. It is used primarily by udev to add the relevant properties |
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38 | to matching devices, but it can also be queried directly.</para> |
39 | </refsect1> | |
40 | ||
41 | <refsect1><title>Hardware Database Files</title> | |
42 | <para>The hwdb files are read from the files located in the | |
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43 | system hwdb directory <filename>/usr/lib/udev/hwdb.d</filename> and |
44 | the local administration directory <filename>/etc/udev/hwdb.d</filename>. | |
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45 | All hwdb files are collectively sorted and processed in lexical order, |
46 | regardless of the directories in which they live. However, files with | |
47 | identical filenames replace each other. Files in <filename>/etc</filename> | |
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48 | have the highest priority and take precedence over files with the same |
49 | name in <filename>/usr/lib</filename>. This can be used to override a | |
50 | system-supplied hwdb file with a local file if needed; | |
65eb4378 | 51 | a symlink in <filename>/etc</filename> with the same name as a hwdb file in |
12b42c76 | 52 | <filename>/usr/lib</filename>, pointing to <filename>/dev/null</filename>, |
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53 | disables the hwdb file entirely. hwdb files must have the extension |
54 | <filename>.hwdb</filename>; other extensions are ignored.</para> | |
55 | ||
56 | <para>The hwdb file contains data records consisting of matches and | |
57 | associated key-value pairs. Every record in the hwdb starts with one or | |
b938cb90 | 58 | more match strings, specifying a shell glob to compare the database |
65eb4378 | 59 | lookup string against. Multiple match lines are specified in additional |
a8eaaee7 | 60 | consecutive lines. Every match line is compared individually, and they are |
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61 | combined by OR. Every match line must start at the first character of |
62 | the line.</para> | |
63 | ||
64 | <para>The match lines are followed by one or more key-value pair lines, which | |
65 | are recognized by a leading space character. The key name and value are separated | |
66 | by <literal>=</literal>. An empty line signifies the end | |
67 | of a record. Lines beginning with <literal>#</literal> are ignored.</para> | |
68 | ||
69 | <para>The content of all hwdb files is read by | |
70 | <citerefentry><refentrytitle>systemd-hwdb</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
71 | and compiled to a binary database located at <filename>/etc/udev/hwdb.bin</filename>, | |
12b42c76 | 72 | or alternatively <filename>/usr/lib/udev/hwdb.bin</filename> if you want ship the compiled |
65eb4378 | 73 | database in an immutable image. |
b938cb90 | 74 | During runtime, only the binary database is used.</para> |
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75 | </refsect1> |
76 | ||
77 | <refsect1> | |
78 | <title>See Also</title> | |
79 | <para> | |
80 | <citerefentry> | |
81 | <refentrytitle>systemd-hwdb</refentrytitle><manvolnum>8</manvolnum> | |
82 | </citerefentry> | |
83 | </para> | |
84 | </refsect1> | |
85 | </refentry> |