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tmpfiles: use write(2) for the 'w' action
[elogind.git] / man / tmpfiles.d.xml
1 <?xml version="1.0"?>
2 <!--*-nxml-*-->
3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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7   Copyright 2010 Brandon Philips
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22 <refentry id="tmpfiles.d">
23
24         <refentryinfo>
25                 <title>tmpfiles.d</title>
26                 <productname>systemd</productname>
27
28                 <authorgroup>
29                         <author>
30                                 <contrib>Documentation</contrib>
31                                 <firstname>Brandon</firstname>
32                                 <surname>Philips</surname>
33                                 <email>brandon@ifup.org</email>
34                         </author>
35                 </authorgroup>
36         </refentryinfo>
37
38         <refmeta>
39                 <refentrytitle>tmpfiles.d</refentrytitle>
40                 <manvolnum>5</manvolnum>
41         </refmeta>
42
43         <refnamediv>
44                 <refname>tmpfiles.d</refname>
45                 <refpurpose>Configuration for creation, deletion and
46                 cleaning of volatile and temporary files</refpurpose>
47         </refnamediv>
48
49         <refsynopsisdiv>
50                 <para><filename>/etc/tmpfiles.d/*.conf</filename></para>
51                 <para><filename>/run/tmpfiles.d/*.conf</filename></para>
52                 <para><filename>/usr/lib/tmpfiles.d/*.conf</filename></para>
53         </refsynopsisdiv>
54
55         <refsect1>
56                 <title>Description</title>
57
58                 <para><command>systemd-tmpfiles</command> uses the
59                 configuration files from the above directories to describe the
60                 creation, cleaning and removal of volatile and
61                 temporary files and directories which usually reside
62                 in directories such as <filename>/run</filename>
63                 or <filename>/tmp</filename>.</para>
64         </refsect1>
65
66         <refsect1>
67                 <title>Configuration Format</title>
68
69                 <para>Each configuration file shall be named in the
70                 style of <filename>&lt;program&gt;.conf</filename>.
71                 Files in <filename>/etc/</filename> override files
72                 with the same name in <filename>/usr/lib/</filename>
73                 and <filename>/run/</filename>.  Files in
74                 <filename>/run/</filename> override files with the same
75                 name in <filename>/usr/lib/</filename>. Packages
76                 should install their configuration files in
77                 <filename>/usr/lib/</filename>. Files in
78                 <filename>/etc/</filename> are reserved for the local
79                 administrator, who may use this logic to override the
80                 configuration files installed by vendor packages. All
81                 configuration files are sorted by their filename in
82                 alphabetical order, regardless in which of the
83                 directories they reside, to guarantee that a specific
84                 configuration file takes precedence over another file
85                 with an alphabetically later name.</para>
86
87                 <para>If the administrator wants to disable a
88                 configuration file supplied by the vendor the
89                 recommended way is to place a symlink to
90                 <filename>/dev/null</filename> in
91                 <filename>/etc/tmpfiles.d/</filename> bearing the
92                 same file name.</para>
93
94                 <para>The configuration format is one line per path
95                 containing action, path, mode, ownership, age and argument
96                 fields:</para>
97
98                 <programlisting>Type Path        Mode UID  GID  Age Argument
99 d    /run/user   0755 root root 10d -
100 L    /tmp/foobar -    -    -    -   /dev/null</programlisting>
101
102                 <refsect2>
103                         <title>Type</title>
104                         <variablelist>
105                                 <varlistentry>
106                                         <term><varname>f</varname></term>
107                                         <listitem><para>Create a file if it doesn't exist yet (optionally writing a short string into it, if the argument parameter is passed)</para></listitem>
108                                 </varlistentry>
109
110                                 <varlistentry>
111                                         <term><varname>F</varname></term>
112                                         <listitem><para>Create or truncate a file (optionally writing a short string into it, if the argument parameter is passed)</para></listitem>
113                                 </varlistentry>
114
115                                 <varlistentry>
116                                         <term><varname>w</varname></term>
117                                         <listitem><para>Write the argument parameter to a file, if the file exists.
118                                             Lines of this type accept shell-style globs in place of normal path
119                                             names. The argument parameter will be written without a trailing
120                                             newline. C-style backslash escapes are interpreted.</para></listitem>
121                                 </varlistentry>
122
123                                 <varlistentry>
124                                         <term><varname>d</varname></term>
125                                         <listitem><para>Create a directory if it doesn't exist yet</para></listitem>
126                                 </varlistentry>
127
128                                 <varlistentry>
129                                         <term><varname>D</varname></term>
130                                         <listitem><para>Create or empty a directory</para></listitem>
131                                 </varlistentry>
132
133                                 <varlistentry>
134                                         <term><varname>p</varname></term>
135                                         <listitem><para>Create a named pipe (FIFO) if it doesn't exist yet</para></listitem>
136                                 </varlistentry>
137
138                                 <varlistentry>
139                                         <term><varname>L</varname></term>
140                                         <listitem><para>Create a symlink if it doesn't exist yet</para></listitem>
141                                 </varlistentry>
142
143                                 <varlistentry>
144                                         <term><varname>c</varname></term>
145                                         <listitem><para>Create a character device node if it doesn't exist yet</para></listitem>
146                                 </varlistentry>
147
148                                 <varlistentry>
149                                         <term><varname>b</varname></term>
150                                         <listitem><para>Create a block device node if it doesn't exist yet</para></listitem>
151                                 </varlistentry>
152
153                                 <varlistentry>
154                                         <term><varname>x</varname></term>
155                                         <listitem><para>Ignore a path
156                                         during cleaning. Use this type
157                                         to exclude paths from clean-up
158                                         as controlled with the Age
159                                         parameter. Note that lines of
160                                         this type do not influence the
161                                         effect of r or R lines. Lines
162                                         of this type accept
163                                         shell-style globs in place of
164                                         of normal path
165                                         names.</para></listitem>
166                                 </varlistentry>
167
168                                 <varlistentry>
169                                         <term><varname>r</varname></term>
170                                         <listitem><para>Remove a file
171                                         or directory if it
172                                         exists. This may not be used
173                                         to remove non-empty
174                                         directories, use R for
175                                         that. Lines of this type
176                                         accept shell-style globs in
177                                         place of normal path
178                                         names.</para></listitem>
179                                 </varlistentry>
180
181                                 <varlistentry>
182                                         <term><varname>R</varname></term>
183                                         <listitem><para>Recursively
184                                         remove a path and all its
185                                         subdirectories (if it is a
186                                         directory). Lines of this type
187                                         accept shell-style globs in
188                                         place of normal path
189                                         names.</para></listitem>
190                                 </varlistentry>
191
192                                 <varlistentry>
193                                         <term><varname>z</varname></term>
194                                         <listitem><para>Restore
195                                         SELinux security context label
196                                         and set ownership and access
197                                         mode of a file or directory if
198                                         it exists.  Lines of this type
199                                         accept shell-style globs in
200                                         place of normal path names.
201                                         </para></listitem>
202                                 </varlistentry>
203
204                                 <varlistentry>
205                                         <term><varname>Z</varname></term>
206                                         <listitem><para>Recursively
207                                         restore SELinux security
208                                         context label and set
209                                         ownership and access mode of a
210                                         path and all its
211                                         subdirectories (if it is a
212                                         directory). Lines of this type
213                                         accept shell-style globs in
214                                         place of normal path
215                                         names.</para></listitem>
216                                 </varlistentry>
217                         </variablelist>
218                 </refsect2>
219
220                 <refsect2>
221                         <title>Mode</title>
222
223                         <para>The file access mode to use when
224                         creating this file or directory. If omitted or
225                         when set to - the default is used: 0755 for
226                         directories, 0644 for all other file
227                         objects. For z, Z lines if omitted or when set
228                         to - the file access mode will not be
229                         modified. This parameter is ignored for x, r,
230                         R, L lines.</para>
231                 </refsect2>
232
233                 <refsect2>
234                         <title>UID, GID</title>
235
236                         <para>The user and group to use for this file
237                         or directory. This may either be a numeric
238                         user/group ID or a user or group name. If
239                         omitted or when set to - the default 0 (root)
240                         is used. For z, Z lines when omitted or when set to -
241                         the file ownership will not be modified.
242                         These parameters are ignored for x, r, R, L lines.</para>
243                 </refsect2>
244
245                 <refsect2>
246                         <title>Age</title>
247                         <para>The date field, when set, is used to
248                         decide what files to delete when cleaning. If
249                         a file or directory is older than the current
250                         time minus the age field it is deleted. The
251                         field format is a series of integers each
252                         followed by one of the following
253                         postfixes for the respective time units:</para>
254
255                         <variablelist>
256                                 <varlistentry>
257                                 <term><varname>s</varname></term>
258                                 <term><varname>min</varname></term>
259                                 <term><varname>h</varname></term>
260                                 <term><varname>d</varname></term>
261                                 <term><varname>w</varname></term>
262                                 <term><varname>ms</varname></term>
263                                 <term><varname>m</varname></term>
264                                 <term><varname>us</varname></term></varlistentry>
265                         </variablelist>
266
267                         <para>If multiple integers and units are specified the time
268                         values are summed up.</para>
269
270                         <para>The age field only applies to lines starting with
271                         d, D and x. If omitted or set to - no automatic clean-up
272                         is done.</para>
273
274                         <para>If the age field starts with a tilde
275                         character (~) the clean-up is only applied to
276                         files and directories one level inside the
277                         directory specified, but not the files and
278                         directories immediately inside it.</para>
279                 </refsect2>
280
281                 <refsect2>
282                         <title>Argument</title>
283
284                         <para>For L lines determines the destination
285                         path of the symlink. For c, b determines the
286                         major/minor of the device node, with major and
287                         minor formatted as integers, separated by :,
288                         e.g. "1:3". For f, F, w may be used to specify
289                         a short string that is written to the file,
290                         suffixed by a newline. Ignored for all other
291                         lines.</para>
292                 </refsect2>
293
294         </refsect1>
295
296         <refsect1>
297                 <title>Example</title>
298                 <example>
299                         <title>/etc/tmpfiles.d/screen.conf example</title>
300                         <para><command>screen</command> needs two directories created at boot with specific modes and ownership.</para>
301
302                         <programlisting>d /var/run/screens  1777 root root 10d
303 d /var/run/uscreens 0755 root root 10d12h</programlisting>
304                 </example>
305         </refsect1>
306
307         <refsect1>
308                 <title>See Also</title>
309                 <para>
310                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
311                         <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
312                         <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>
313                 </para>
314         </refsect1>
315
316 </refentry>