systemd/man/tmpfiles.d.xml

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<refentry id="tmpfiles.d">

        <refentryinfo>
                <title>tmpfiles.d</title>
                <productname>systemd</productname>

                <authorgroup>
                        <author>
                                <contrib>Documentation</contrib>
                                <firstname>Brandon</firstname>
                                <surname>Philips</surname>
                                <email>brandon@ifup.org</email>
                        </author>
                </authorgroup>
        </refentryinfo>

        <refmeta>
                <refentrytitle>tmpfiles.d</refentrytitle>
                <manvolnum>5</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>tmpfiles.d</refname>
                <refpurpose>Configuration for creation, deletion and
                cleaning of volatile and temporary files</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <para><filename>/etc/tmpfiles.d/*.conf</filename></para>
                <para><filename>/run/tmpfiles.d/*.conf</filename></para>
                <para><filename>/usr/lib/tmpfiles.d/*.conf</filename></para>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><command>systemd-tmpfiles</command> uses the
                configuration files from the above directories to describe the
                creation, cleaning and removal of volatile and
                temporary files and directories which usually reside
                in directories such as <filename>/run</filename>
                or <filename>/tmp</filename>.</para>

                <para>Volatile and temporary files and directories are
                those located in <filename>/run</filename> (and its
                alias <filename>/var/run</filename>),
                <filename>/tmp</filename>,
                <filename>/var/tmp</filename>, the API file systems
                such as <filename>/sys</filename> or
                <filename>/proc</filename>, as well as some other
                directories below <filename>/var</filename>.</para>

                <para>System daemons frequently require private
                runtime directories below <filename>/run</filename> to
                place communication sockets and similar in. For these,
                consider declaring them in their unit files using
                <varname>RuntimeDirectory=</varname>
                (see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details),
                if this is feasible.</para>
        </refsect1>

        <refsect1>
                <title>Configuration Format</title>

                <para>Each configuration file shall be named in the
                style of
                <filename><replaceable>package</replaceable>.conf</filename>
                or
                <filename><replaceable>package</replaceable>-<replaceable>part</replaceable>.conf</filename>.
                The second variant should be used when it is desirable
                to make it easy to override just this part of
                configuration.</para>

                <para>Files in <filename>/etc/tmpfiles.d</filename>
                override files with the same name in
                <filename>/usr/lib/tmpfiles.d</filename> and
                <filename>/run/tmpfiles.d</filename>. Files in
                <filename>/run/tmpfiles.d</filename> override files
                with the same name in
                <filename>/usr/lib/tmpfiles.d</filename>. Packages
                should install their configuration files in
                <filename>/usr/lib/tmpfiles.d</filename>. Files in
                <filename>/etc/tmpfiles.d</filename> are reserved for
                the local administrator, who may use this logic to
                override the configuration files installed by vendor
                packages. All configuration files are sorted by their
                filename in lexicographic order, regardless of which
                of the directories they reside in. If multiple files
                specify the same path, the entry in the file with the
                lexicographically earliest name will be applied.
                All other conflicting entries will be logged as
                errors. When two lines are prefix and suffix of each
                other, then the prefix is always processed first, the
                suffix later. Otherwise, the files/directories are
                processed in the order they are listed.</para>

                <para>If the administrator wants to disable a
                configuration file supplied by the vendor, the
                recommended way is to place a symlink to
                <filename>/dev/null</filename> in
                <filename>/etc/tmpfiles.d/</filename> bearing the
                same filename.</para>

                <para>The configuration format is one line per path
                containing type, path, mode, ownership, age, and argument
                fields:</para>

                <programlisting>#Type Path        Mode UID  GID  Age Argument
d    /run/user   0755 root root 10d -
L    /tmp/foobar -    -    -    -   /dev/null</programlisting>

                <refsect2>
                        <title>Type</title>

                        <para>The type consists of a single letter and
                        optionally an exclamation mark.</para>

                        <para>The following line types are understood:</para>

                        <variablelist>
                                <varlistentry>
                                        <term><varname>f</varname></term>
                                        <listitem><para>Create a file if it does not exist yet. If the argument parameter is given, it will be written to the file.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>F</varname></term>
                                        <listitem><para>Create or truncate a file. If the argument parameter is given, it will be written to the file.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>w</varname></term>
                                        <listitem><para>Write the argument parameter to a file, if the file exists.
                                            Lines of this type accept shell-style globs in place of normal path
                                            names. The argument parameter will be written without a trailing
                                            newline. C-style backslash escapes are interpreted.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>d</varname></term>
                                        <listitem><para>Create a directory if it does not exist yet.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>D</varname></term>
                                        <listitem><para>Create or empty a directory.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>v</varname></term>
                                        <listitem><para>Create a
                                        subvolume if the path does not
                                        exist yet and the file system
                                        supports this (btrfs). Otherwise
                                        create a normal directory, in
                                        the same way as
                                        <varname>d</varname>.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>p</varname></term>
                                        <term><varname>p+</varname></term>
                                        <listitem><para>Create a named
                                        pipe (FIFO) if it does not
                                        exist yet. If suffixed with
                                        <varname>+</varname> and a
                                        file already exists where the
                                        pipe is to be created, it will
                                        be removed and be replaced by
                                        the pipe.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>L</varname></term>
                                        <term><varname>L+</varname></term>
                                        <listitem><para>Create a
                                        symlink if it does not exist
                                        yet. If suffixed with
                                        <varname>+</varname> and a
                                        file already exists where the
                                        symlink is to be created, it
                                        will be removed and be
                                        replaced by the
                                        symlink. If the argument is omitted,
                                        symlinks to files with the same name
                                        residing in the directory
                                        <filename>/usr/share/factory/</filename>
                                        are created.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>c</varname></term>
                                        <term><varname>c+</varname></term>
                                        <listitem><para>Create a
                                        character device node if it
                                        does not exist yet. If
                                        suffixed with
                                        <varname>+</varname> and a
                                        file already exists where the
                                        device node is to be created,
                                        it will be removed and be
                                        replaced by the device
                                        node. It is recommended to suffix this
                                        entry with an exclamation mark to only
                                        create static device nodes at boot,
                                        as udev will not manage static device
                                        nodes that are created at runtime.
                                        </para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>b</varname></term>
                                        <term><varname>b+</varname></term>
                                        <listitem><para>Create a block
                                        device node if it does not
                                        exist yet. If suffixed with
                                        <varname>+</varname> and a
                                        file already exists where the
                                        device node is to be created,
                                        it will be removed and be
                                        replaced by the device
                                        node. It is recommended to suffix this
                                        entry with an exclamation mark to only
                                        create static device nodes at boot,
                                        as udev will not manage static device
                                        nodes that are created at runtime.
                                        </para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>C</varname></term>
                                        <listitem><para>Recursively
                                        copy a file or directory, if
                                        the destination files or
                                        directories do not exist
                                        yet. Note that this command
                                        will not descend into
                                        subdirectories if the
                                        destination directory already
                                        exists. Instead, the entire
                                        copy operation is
                                        skipped. If the argument is omitted,
                                        files from the source directory
                                        <filename>/usr/share/factory/</filename>
                                        with the same name are copied.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>x</varname></term>
                                        <listitem><para>Ignore a path
                                        during cleaning. Use this type
                                        to exclude paths from clean-up
                                        as controlled with the Age
                                        parameter. Note that lines of
                                        this type do not influence the
                                        effect of <varname>r</varname>
                                        or <varname>R</varname> lines.
                                        Lines of this type accept
                                        shell-style globs in place of
                                        normal path names.
                                        </para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>X</varname></term>
                                        <listitem><para>Ignore a path
                                        during cleaning. Use this type
                                        to exclude paths from clean-up
                                        as controlled with the Age
                                        parameter. Unlike
                                        <varname>x</varname>, this
                                        parameter will not exclude the
                                        content if path is a
                                        directory, but only directory
                                        itself. Note that lines of
                                        this type do not influence the
                                        effect of <varname>r</varname>
                                        or <varname>R</varname> lines.
                                        Lines of this type accept
                                        shell-style globs in place of
                                        normal path names.
                                        </para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>r</varname></term>
                                        <listitem><para>Remove a file
                                        or directory if it exists.
                                        This may not be used to remove
                                        non-empty directories, use
                                        <varname>R</varname> for that.
                                        Lines of this type accept
                                        shell-style globs in place of
                                        normal path
                                        names.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>R</varname></term>
                                        <listitem><para>Recursively
                                        remove a path and all its
                                        subdirectories (if it is a
                                        directory). Lines of this type
                                        accept shell-style globs in
                                        place of normal path
                                        names.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>z</varname></term>
                                        <listitem><para>Adjust the
                                        access mode, group and user,
                                        and restore the SELinux security
                                        context of a file or directory,
                                        if it exists. Lines of this
                                        type accept shell-style globs
                                        in place of normal path names.
                                        </para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>Z</varname></term>
                                        <listitem><para>Recursively
                                        set the access mode, group and
                                        user, and restore the SELinux
                                        security context of a file or
                                        directory if it exists, as
                                        well as of its subdirectories
                                        and the files contained
                                        therein (if applicable). Lines
                                        of this type accept
                                        shell-style globs in place of
                                        normal path
                                        names.</para></listitem>
                                </varlistentry>

                                <varlistentry>
                                        <term><varname>t</varname></term>
                                        <listitem><para>Set extended
                                        attributes on item. It may be
                                        used in conjunction with other
                                        types (only <varname>d</varname>,
                                        <varname>D</varname>, <varname>f</varname>,
                                        <varname>F</varname>, <varname>L</varname>,
                                        <varname>p</varname>, <varname>c</varname>,
                                        <varname>b</varname>, makes sense).
                                        If used as a standalone line, then
                                        <command>systemd-tmpfiles</command>
                                        will try to set extended
                                        attributes on specified path.
                                        This can be especially used to set
                                        SMACK labels.
                                        </para></listitem>
                                </varlistentry>
                        </variablelist>

                        <para>If the exclamation mark is used, this
                        line is only safe of execute during boot, and
                        can break a running system. Lines without the
                        exclamation mark are presumed to be safe to
                        execute at any time, e.g. on package upgrades.
                        <command>systemd-tmpfiles</command> will
                        execute line with an exclamation mark only if
                        option <option>--boot</option> is given.
                        </para>

                        <para>For example:
                        <programlisting># Make sure these are created by default so that nobody else can
d /tmp/.X11-unix 1777 root root 10d

# Unlink the X11 lock files
r! /tmp/.X[0-9]*-lock</programlisting>
                        The second line in contrast to the first one
                        would break a running system, and will only be
                        executed with <option>--boot</option>.</para>
                </refsect2>

                <refsect2>
                        <title>Path</title>

                        <para>The file system path specification supports simple specifier
                        expansion. The following expansions are
                        understood:</para>

                        <table>
                                <title>Specifiers available</title>
                                <tgroup cols='3' align='left' colsep='1' rowsep='1'>
                                        <colspec colname="spec" />
                                        <colspec colname="mean" />
                                        <colspec colname="detail" />
                                        <thead>
                                                <row>
                                                        <entry>Specifier</entry>
                                                        <entry>Meaning</entry>
                                                        <entry>Details</entry>
                                                </row>
                                        </thead>
                                        <tbody>
                                                <row>
                                                        <entry><literal>%m</literal></entry>
                                                        <entry>Machine ID</entry>
                                                        <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
                                                </row>
                                                <row>
                                                        <entry><literal>%b</literal></entry>
                                                        <entry>Boot ID</entry>
                                                        <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
                                                </row>
                                                <row>
                                                        <entry><literal>%H</literal></entry>
                                                        <entry>Host name</entry>
                                                        <entry>The hostname of the running system.</entry>
                                                </row>
                                                <row>
                                                        <entry><literal>%v</literal></entry>
                                                        <entry>Kernel release</entry>
                                                        <entry>Identical to <command>uname -r</command> output.</entry>
                                                </row>
                                                <row>
                                                        <entry><literal>%%</literal></entry>
                                                        <entry>Escaped %</entry>
                                                        <entry>Single percent sign.</entry>
                                                </row>
                                        </tbody>
                                </tgroup>
                        </table>
                </refsect2>

                <refsect2>
                        <title>Mode</title>

                        <para>The file access mode to use when
                        creating this file or directory. If omitted or
                        when set to -, the default is used: 0755 for
                        directories, 0644 for all other file objects.
                        For <varname>z</varname>, <varname>Z</varname>
                        lines, if omitted or when set to
                        <literal>-</literal>, the file access mode
                        will not be modified. This parameter is
                        ignored for <varname>x</varname>,
                        <varname>r</varname>, <varname>R</varname>,
                        <varname>L</varname>, <varname>t</varname> lines.</para>

                        <para>Optionally, if prefixed with
                        <literal>~</literal>, the access mode is masked
                        based on the already set access bits for
                        existing file or directories: if the existing
                        file has all executable bits unset, all
                        executable bits are removed from the new
                        access mode, too. Similarly, if all read bits
                        are removed from the old access mode, they will
                        be removed from the new access mode too, and
                        if all write bits are removed, they will be
                        removed from the new access mode too. In
                        addition, the sticky/SUID/SGID bit is removed unless
                        applied to a directory. This
                        functionality is particularly useful in
                        conjunction with <varname>Z</varname>.</para>
                </refsect2>

                <refsect2>
                        <title>UID, GID</title>

                        <para>The user and group to use for this file
                        or directory. This may either be a numeric
                        user/group ID or a user or group name. If
                        omitted or when set to <literal>-</literal>,
                        the default 0 (root) is used. For
                        <varname>z</varname>, <varname>Z</varname>
                        lines, when omitted or when set to -, the file
                        ownership will not be modified. These
                        parameters are ignored for
                        <varname>x</varname>, <varname>r</varname>,
                        <varname>R</varname>, <varname>L</varname>,
                        <varname>t</varname> lines.</para>
                </refsect2>

                <refsect2>
                        <title>Age</title>
                        <para>The date field, when set, is used to
                        decide what files to delete when cleaning. If
                        a file or directory is older than the current
                        time minus the age field, it is deleted. The
                        field format is a series of integers each
                        followed by one of the following
                        postfixes for the respective time units:</para>

                        <variablelist>
                                <varlistentry>
                                <term><varname>s</varname></term>
                                <term><varname>min</varname></term>
                                <term><varname>h</varname></term>
                                <term><varname>d</varname></term>
                                <term><varname>w</varname></term>
                                <term><varname>ms</varname></term>
                                <term><varname>m</varname></term>
                                <term><varname>us</varname></term></varlistentry>
                        </variablelist>

                        <para>If multiple integers and units are specified, the time
                        values are summed up. If an integer is given without a unit,
                        s is assumed.
                        </para>

                        <para>When the age is set to zero, the files are cleaned
                        unconditionally.</para>

                        <para>The age field only applies to lines
                        starting with <varname>d</varname>,
                        <varname>D</varname>, and
                        <varname>x</varname>. If omitted or set to
                        <literal>-</literal>, no automatic clean-up is
                        done.</para>

                        <para>If the age field starts with a tilde
                        character <literal>~</literal>, the clean-up
                        is only applied to files and directories one
                        level inside the directory specified, but not
                        the files and directories immediately inside
                        it.</para>
                </refsect2>

                <refsect2>
                        <title>Argument</title>

                        <para>For <varname>L</varname> lines
                        determines the destination path of the
                        symlink. For <varname>c</varname>,
                        <varname>b</varname> determines the
                        major/minor of the device node, with major and
                        minor formatted as integers, separated by
                        <literal>:</literal>, e.g.
                        <literal>1:3</literal>. For
                        <varname>f</varname>, <varname>F</varname>,
                        and <varname>w</varname> may be used to
                        specify a short string that is written to the
                        file, suffixed by a newline. For
                        <varname>C</varname>, specifies the source file
                        or directory. For <varname>t</varname> determines
                        extended attributes to be set. Ignored for all other lines.</para>
                </refsect2>

        </refsect1>

        <refsect1>
                <title>Example</title>
                <example>
                        <title>/etc/tmpfiles.d/screen.conf example</title>
                        <para><command>screen</command> needs two directories created at boot with specific modes and ownership.</para>

                        <programlisting>d /run/screens  1777 root root 10d
d /run/uscreens 0755 root root 10d12h
t /run/screen - - - - user.name="John Smith" security.SMACK64=screen</programlisting>
                </example>
                <example>
                        <title>/etc/tmpfiles.d/abrt.conf example</title>
                        <para><command>abrt</command> needs a directory created at boot with specific mode and ownership and its content should be preserved.</para>

                        <programlisting>d /var/tmp/abrt 0755 abrt abrt
x /var/tmp/abrt/*</programlisting>
                </example>
        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>