capability: add new ambient_capabilities_supported() helper

[thirdparty/systemd.git] / 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. Lines that take globs are
    applied after those accepting no globs. If multiple operations
    shall be applied on the same file, (such as ACL, xattr, file
    attribute adjustments), these are always done in the same fixed
    order. 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>

    <para>Fields may be enclosed within quotes and contain C-style escapes.</para>

    <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. Does not follow symlinks.</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. Does not follow symlinks.</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. Follows
          symlinks.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>d</varname></term>
          <listitem><para>Create a directory. The mode and ownership will be adjusted if
          specified and the directory already exists. Contents of this directory are subject
          to time based cleanup if the age argument is specified.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>D</varname></term>
          <listitem><para>Similar to <varname>d</varname>, but in addition the contents
          of the directory will be removed when <option>--remove</option> is used.
          </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>e</varname></term>
          <listitem><para>Similar to <varname>d</varname>, but the directory will not be created if
          it does not exist. Lines of this type accept shell-style globs in place of normal path
          names. For this entry to be useful, at least one of the mode, uid, gid, or age arguments
          must be specified, since otherwise this entry has no effect. If the age argument is
          <literal>0</literal>, contents of the directory will be unconditionally deleted every time
          <command>systemd-tmpfiles --clean</command> is run. This can be useful when combined with
          <varname>!</varname>, see the examples.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>v</varname></term>
          <listitem><para>Create a subvolume if the path does not
          exist yet, the file system supports subvolumes (btrfs), and
          the system itself is installed into a subvolume
          (specifically: the root directory <filename>/</filename> is
          itself a subvolume). Otherwise, create a normal directory, in
          the same way as <varname>d</varname>. A subvolume created
          with this line type is not assigned to any higher-level
          quota group. For that, use <varname>q</varname> or
          <varname>Q</varname>, which allow creating simple quota
          group hierarchies, see below.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>q</varname></term>
          <listitem><para>Similar to <varname>v</varname>. However,
          makes sure that the subvolume will be assigned to the same
          higher-level quota groups as the subvolume it has been
          created in. This ensures that higher-level limits and
          accounting applied to the parent subvolume also include the
          specified subvolume. On non-btrfs file systems, this line
          type is identical to <varname>d</varname>. If the subvolume
          already exists and is already assigned to one or more higher
          level quota groups, no change to the quota hierarchy is
          made. Also see <varname>Q</varname> below. See <citerefentry
          project='die-net'><refentrytitle>btrfs-qgroup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          for details about the btrfs quota group
          concept.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>Q</varname></term>
          <listitem><para>Similar to <varname>q</varname>. However,
          instead of copying the higher-level quota group assignments
          from the parent as-is, the lowest quota group of the parent
          subvolume is determined that is not the leaf quota
          group. Then, an "intermediary" quota group is inserted that
          is one level below this level, and shares the same ID part
          as the specified subvolume. If no higher-level quota group
          exists for the parent subvolume, a new quota group at level
          255 sharing the same ID as the specified subvolume is
          inserted instead. This new intermediary quota group is then
          assigned to the parent subvolume's higher-level quota
          groups, and the specified subvolume's leaf quota group is
          assigned to it.</para>

          <para>Effectively, this has a similar effect as
          <varname>q</varname>, however introduces a new higher-level
          quota group for the specified subvolume that may be used to
          enforce limits and accounting to the specified subvolume and
          children subvolume created within it. Thus, by creating
          subvolumes only via <varname>q</varname> and
          <varname>Q</varname>, a concept of "subtree quotas" is
          implemented. Each subvolume for which <varname>Q</varname>
          is set will get a "subtree" quota group created, and all
          child subvolumes created within it will be assigned to
          it. Each subvolume for which <varname>q</varname> is set
          will not get such a "subtree" quota group, but it is ensured
          that they are added to the same "subtree" quota group as their
          immediate parents.</para>

          <para>It is recommended to use
          <varname>Q</varname> for subvolumes that typically contain
          further subvolumes, and where it is desirable to have
          accounting and quota limits on all child subvolumes
          together. Examples for <varname>Q</varname> are typically
          <filename>/home</filename> or
          <filename>/var/lib/machines</filename>. In contrast,
          <varname>q</varname> should be used for subvolumes that
          either usually do not include further subvolumes or where no
          accounting and quota limits are needed that apply to all
          child subvolumes together. Examples for <varname>q</varname>
          are typically <filename>/var</filename> or
          <filename>/var/tmp</filename>. As with <varname>Q</varname>,
          <varname>q</varname> has no effect on the quota group
          hierarchy if the subvolume exists and already has at least
          one higher-level quota group assigned.</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 or
          directory 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. Note
          that permissions and ownership on symlinks are ignored.
          </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. Does not follow symlinks.</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. Does not follow symlinks.</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. Does not follow symlinks.</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. Does not follow symlinks.</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. Does not follow symlinks.  </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>t</varname></term>
          <listitem><para>Set extended attributes. Lines of this type
          accept shell-style globs in place of normal path names.
          This can be useful for setting SMACK labels. Does not follow
          symlinks.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>T</varname></term>
          <listitem><para>Recursively set extended attributes. Lines
          of this type accept shell-style globs in place of normal
          path names.  This can be useful for setting SMACK
          labels. Does not follow symlinks.  </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>h</varname></term>
          <listitem><para>Set file/directory attributes. Lines of this type
          accept shell-style globs in place of normal path names.</para>

          <para>The format of the argument field is
          <varname>[+-=][aAcCdDeijsStTu] </varname>. The prefix
          <varname>+</varname> (the default one) causes the
          attribute(s) to be added; <varname>-</varname> causes the
          attribute(s) to be removed; <varname>=</varname> causes the
          attributes to be set exactly as the following letters. The
          letters <literal>aAcCdDeijsStTu</literal> select the new
          attributes for the files, see
          <citerefentry project='man-pages'><refentrytitle>chattr</refentrytitle>
          <manvolnum>1</manvolnum></citerefentry> for further information.
          </para>
          <para>Passing only <varname>=</varname> as argument resets
          all the file attributes listed above. It has to be pointed
          out that the <varname>=</varname> prefix limits itself to
          the attributes corresponding to the letters listed here. All
          other attributes will be left untouched. Does not follow
          symlinks.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>H</varname></term>
          <listitem><para>Recursively set file/directory attributes. Lines
          of this type accept shell-style globs in place of normal
          path names. Does not follow symlinks.
          </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>a</varname></term>
          <term><varname>a+</varname></term>
          <listitem><para>Set POSIX ACLs (access control lists). If
          suffixed with <varname>+</varname>, the specified entries will
          be added to the existing set.
          <command>systemd-tmpfiles</command> will automatically add
          the required base entries for user and group based on the
          access mode of the file, unless base entries already exist
          or are explicitly specified. The mask will be added if not
          specified explicitly or already present. Lines of this type
          accept shell-style globs in place of normal path names. This
          can be useful for allowing additional access to certain
          files. Does not follow symlinks.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><varname>A</varname></term>
          <term><varname>A+</varname></term>
          <listitem><para>Same as <varname>a</varname> and
          <varname>a+</varname>, but recursive. Does not follow
          symlinks.</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 <literal>-</literal>, 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>,
      and <varname>a</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> and
      <varname>Z</varname> lines, when omitted or when set to
      <literal>-</literal>, 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>, and
      <varname>a</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 suffixes for the respective time units:
      <constant>s</constant>,
      <constant>m</constant> or <constant>min</constant>,
      <constant>h</constant>,
      <constant>d</constant>,
      <constant>w</constant>,
      <constant>ms</constant>, and
      <constant>us</constant>,
      meaning seconds, minutes, hours, days, weeks,
      milliseconds, and microseconds, respectively. Full names of the time units can
      be used too.
      </para>

      <para>If multiple integers and units are specified, the time
      values are summed. If an integer is given without a unit,
      <constant>s</constant> 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>, <varname>e</varname>,
      <varname>v</varname>, <varname>q</varname>,
      <varname>Q</varname>, <varname>C</varname>, <varname>x</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> and
      <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>, the argument 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> and <varname>T</varname>,
      determines extended attributes to be set. For
      <varname>a</varname> and <varname>A</varname>, determines ACL
      attributes to be set. For <varname>h</varname> and
      <varname>H</varname>, determines the file attributes to
      set. Ignored for all other lines.</para>
    </refsect2>

  </refsect1>

  <refsect1>
    <title>Examples</title>
    <example>
      <title>Create directories with specific mode and ownership</title>
      <para>
      <citerefentry project='die-net'><refentrytitle>screen</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      needs two directories created at boot with specific modes and ownership:</para>

      <programlisting># /usr/lib/tmpfiles.d/screen.conf
d /run/screens  1777 root screen 10d
d /run/uscreens 0755 root screen 10d12h
</programlisting>

      <para>Contents of <filename>/run/screens</filename> and /run/uscreens will
      cleaned up after 10 and 10½ days, respectively.</para>
    </example>

    <example>
      <title>Create a directory with a SMACK attribute</title>
      <programlisting>D /run/cups - - - -
t /run/cups - - - - security.SMACK64=printing user.attr-with-spaces="foo bar"
      </programlisting>

      <para>The directory will be owned by root and have default mode. Its contents are
      not subject to time based cleanup, but will be obliterated when
      <command>systemd-tmpfiles --remove</command> runs.</para>
    </example>

    <example>
      <title>Create a directory and prevent its contents from cleanup</title>
      <para>
      <citerefentry project='die-net'><refentrytitle>abrt</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      needs a directory created at boot with specific mode and ownership and its content
      should be preserved from the automatic cleanup applied to the contents of
      <filename>/var/tmp</filename>:</para>

      <programlisting># /usr/lib/tmpfiles.d/tmp.conf
d /var/tmp 1777 root root 30d
</programlisting>

      <programlisting># /usr/lib/tmpfiles.d/abrt.conf
d /var/tmp/abrt 0755 abrt abrt -
</programlisting>
    </example>

    <example>
      <title>Apply clean up during boot and based on time</title>

      <programlisting># /usr/lib/tmpfiles.d/dnf.conf
r! /var/cache/dnf/*/*/download_lock.pid
r! /var/cache/dnf/*/*/metadata_lock.pid
r! /var/lib/dnf/rpmdb_lock.pid
e  /var/chache/dnf/ - - - 30d
</programlisting>

     <para>The lock files will be removed during boot. Any files and directories in
     <filename>/var/chache/dnf/</filename> will be removed after they have not been
     accessed in 30 days.</para>
    </example>

    <example>
      <title>Empty the contents of a cache directory on boot</title>

      <programlisting># /usr/lib/tmpfiles.d/krb5rcache.conf
e! /var/cache/krb5rcache - - - 0
</programlisting>

      <para>Any files and subdirectories in <filename>/var/cache/krb5rcache/</filename>
      will be removed on boot. The directory will not be created.
      </para>
    </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>,
      <citerefentry project='man-pages'><refentrytitle>attr</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>getfattr</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>setfattr</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>getfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>chattr</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='die-net'><refentrytitle>btrfs-subvolume</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry project='die-net'><refentrytitle>btrfs-qgroup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>