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systemd/man/tmpfiles.d.xml
Lennart Poettering 778abdbfa1 doc: fix .ssh credential examples 
Let's create the .ssh dir with the right perms first.

Suggested by @gcb.

Fixes: #28172
2024-04-18 10:53:20 +02:00

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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<!--
SPDX-License-Identifier: LGPL-2.1-or-later
Copyright © 2010 Brandon Philips
-->
<refentry id="tmpfiles.d"
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>tmpfiles.d</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>tmpfiles.d</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>tmpfiles.d</refname>
<refpurpose>Configuration for creation, deletion, and cleaning of files and directories</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><simplelist>
<member><filename>/etc/tmpfiles.d/*.conf</filename></member>
<member><filename>/run/tmpfiles.d/*.conf</filename></member>
<member><filename>/usr/lib/tmpfiles.d/*.conf</filename></member>
</simplelist></para>
<para><simplelist>
<member><filename>~/.config/user-tmpfiles.d/*.conf</filename></member>
<member><filename>$XDG_RUNTIME_DIR/user-tmpfiles.d/*.conf</filename></member>
<member><filename>~/.local/share/user-tmpfiles.d/*.conf</filename></member>
<member><filename index='false'>…</filename></member>
<member><filename>/usr/share/user-tmpfiles.d/*.conf</filename></member>
</simplelist></para>
<programlisting>#Type Path Mode User Group Age Argument
f /file/to/create mode user group - content
f+ /file/to/create-or-truncate mode user group - content
w /file/to/write-to - - - - content
w+ /file/to/append-to - - - - content
d /directory/to/create-and-clean-up mode user group cleanup-age -
D /directory/to/create-and-remove mode user group cleanup-age -
e /directory/to/clean-up mode user group cleanup-age -
v /subvolume-or-directory/to/create mode user group cleanup-age -
q /subvolume-or-directory/to/create mode user group cleanup-age -
Q /subvolume-or-directory/to/create mode user group cleanup-age -
p /fifo/to/create mode user group - -
p+ /fifo/to/[re]create mode user group - -
L /symlink/to/create - - - - symlink/target/path
L+ /symlink/to/[re]create - - - - symlink/target/path
c /dev/char-device-to-create mode user group - major:minor
c+ /dev/char-device-to-[re]create mode user group - major:minor
b /dev/block-device-to-create mode user group - major:minor
b+ /dev/block-device-to-[re]create mode user group - major:minor
C /target/to/create - - - cleanup-age /source/to/copy
C+ /target/to/create - - - cleanup-age /source/to/copy
x /path-or-glob/to/ignore/recursively - - - cleanup-age -
X /path-or-glob/to/ignore - - - cleanup-age -
r /path-or-glob/to/remove - - - - -
R /path-or-glob/to/remove/recursively - - - - -
z /path-or-glob/to/adjust/mode mode user group - -
Z /path-or-glob/to/adjust/mode/recursively mode user group - -
t /path-or-glob/to/set/xattrs - - - - xattrs
T /path-or-glob/to/set/xattrs/recursively - - - - xattrs
h /path-or-glob/to/set/attrs - - - - file attrs
H /path-or-glob/to/set/attrs/recursively - - - - file attrs
a /path-or-glob/to/set/acls - - - - POSIX ACLs
a+ /path-or-glob/to/append/acls - - - - POSIX ACLs
A /path-or-glob/to/set/acls/recursively - - - - POSIX ACLs
A+ /path-or-glob/to/append/acls/recursively - - - - POSIX ACLs
</programlisting>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><filename>tmpfiles.d</filename> configuration files provide a generic mechanism to define the
<emphasis>creation</emphasis> of regular files, directories, pipes, and device nodes, adjustments to
their <emphasis>access mode, ownership, attributes, quota assignments, and contents</emphasis>, and
finally their time-based <emphasis>removal</emphasis>. It is mostly commonly used for volatile and
temporary files and directories (such as those located under <filename>/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><citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>
uses this configuration to create volatile files and directories during boot and to do periodic cleanup
afterwards. See
<citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry> for
the description of <filename>systemd-tmpfiles-setup.service</filename>,
<filename>systemd-tmpfiles-clean.service</filename>, and associated units.</para>
<para>System daemons frequently require private runtime directories below <filename>/run/</filename> to
store communication sockets and similar. For these, it is better to use
<varname>RuntimeDirectory=</varname> in their unit files (see
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
details), if the flexibility provided by <filename>tmpfiles.d</filename> is not required. The advantages
are that the configuration required by the unit is centralized in one place, and that the lifetime of the
directory is tied to the lifetime of the service itself. Similarly, <varname>StateDirectory=</varname>,
<varname>CacheDirectory=</varname>, <varname>LogsDirectory=</varname>, and
<varname>ConfigurationDirectory=</varname> should be used to create directories under
<filename>/var/lib/</filename>, <filename>/var/cache/</filename>, <filename>/var/log/</filename>, and
<filename>/etc/</filename>. <filename>tmpfiles.d</filename> should be used for files whose lifetime is
independent of any service or requires more complicated configuration.</para>
</refsect1>
<refsect1>
<title>Configuration Directories and Precedence</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 (note that lines suppressed due to the
<literal>!</literal> are filtered before application, meaning that if an early line carries the
exclamation mark and is suppressed because of that, a later line matching in path will be applied). All
other conflicting entries will be logged as errors. When two lines are prefix path and suffix path of
each other, then the prefix line is always created first, the suffix later (and if removal applies to the
line, the order is reversed: the suffix is removed first, the prefix 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. Except for those
cases, 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>
</refsect1>
<refsect1>
<title>Configuration File Format</title>
<para>The configuration format is one line per path, containing type, path, mode, ownership, age, and
argument fields. The lines are separated by newlines, the fields by whitespace:</para>
<programlisting>#Type Path Mode User Group Age Argument…
d /run/user 0755 root root 10d -
L /tmp/foobar - - - - /dev/null</programlisting>
<para>Fields may contain C-style escapes. With the exception of the seventh field (the "argument") all
fields may be enclosed in quotes. Note that any whitespace found in the line after the beginning of the
argument field will be considered part of the argument field. To begin the argument field with a
whitespace character, use C-style escapes (e.g. <literal>\x20</literal>).</para>
<refsect2>
<title>Type</title>
<para>The type consists of a single letter and optionally one or more modifier characters: a plus sign
(<literal>+</literal>), exclamation mark (<literal>!</literal>), minus sign (<literal>-</literal>),
equals sign (<literal>=</literal>), tilde character (<literal>~</literal>) and/or caret
(<literal>^</literal>).</para>
<para>The following line types are understood:</para>
<variablelist>
<varlistentry>
<term><varname>f</varname></term>
<term><varname>f+</varname></term>
<listitem><para><varname>f</varname> will create a file if it does not exist yet. If the argument
parameter is given and the file did not exist yet, it will be written to the file.
<varname>f+</varname> will create or truncate the 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>
<term><varname>w+</varname></term>
<listitem><para>Write the argument parameter to a file, if the file exists.
If suffixed with <varname>+</varname>, the line will be appended to the file.
If your configuration writes multiple lines to the same file, use <varname>w+</varname>.
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. 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>Adjust the mode and ownership of existing directories and remove their contents
based on age. Lines of this type accept shell-style globs in place of normal path names. Contents
of the directories are subject to time-based cleanup if the age argument is specified. If the age
argument is <literal>0</literal>, contents will be unconditionally deleted every time
<citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>
<option>--clean</option> is run.</para>
<para>For this entry to be useful, at least one of the mode, user, group, or age arguments must be
specified, since otherwise this entry has no effect. As an exception, an entry with no effect may
be useful when combined with <varname>!</varname>, see the examples.</para>
<xi:include href="version-info.xml" xpointer="v230"/></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>.</para>
<para>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>
<xi:include href="version-info.xml" xpointer="v219"/></listitem>
</varlistentry>
<varlistentry>
<term><varname>q</varname></term>
<listitem><para>Create a subvolume or directory the same as <varname>v</varname>, but assign the
subvolume to the same higher-level quota groups as the parent. 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>.</para>
<para>If the subvolume already exists, no change to the quota hierarchy is made, regardless of whether the
subvolume is already attached to a quota group or not. Also see <varname>Q</varname> below. See
<citerefentry project='url'><refentrytitle url='https://btrfs.readthedocs.io/en/latest/btrfs-qgroup.html'>btrfs-qgroup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details about the btrfs quota group concept.</para>
<xi:include href="version-info.xml" xpointer="v228"/></listitem>
</varlistentry>
<varlistentry>
<term><varname>Q</varname></term>
<listitem><para>Create the subvolume or directory the same as <varname>v</varname>, but assign the
new subvolume to a new leaf quota group. Instead of copying the higher-level quota group
assignments from the parent as is done with <varname>q</varname>, 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>. </para>
<para>As with <varname>q</varname>, <varname>Q</varname> has no effect on the quota group hierarchy if the
subvolume already exists, regardless of whether the subvolume already belong to a quota group or not.
</para>
<xi:include href="version-info.xml" xpointer="v228"/></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>
<term><varname>C+</varname></term>
<listitem><para>Recursively copy a file or directory, if the destination files or directories do
not exist yet or the destination directory is empty. Note that this command will not descend into
subdirectories if the destination directory already exists and is not empty, unless the action is
suffixed with <varname>+</varname>. 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. Contents of the directories are subject to time-based
cleanup if the age argument is specified.
</para>
<xi:include href="version-info.xml" xpointer="v214"/></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. 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. Lines of this type accept
shell-style globs in place of normal path names.
</para>
<xi:include href="version-info.xml" xpointer="v198"/></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, user and group ownership, 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, user and group ownership, 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, see <citerefentry
project='man-pages'><refentrytitle>attr</refentrytitle>
<manvolnum>5</manvolnum></citerefentry> for details. The argument field should take one or more
assignment expressions in the form
<replaceable>namespace</replaceable>.<replaceable>attribute</replaceable>=<replaceable>value</replaceable>,
for examples see below. 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>
<para>Please note that extended attributes settable with this line type are a different concept
from the Linux file attributes settable with <varname>h</varname>/<varname>H</varname>, see
below.</para>
<xi:include href="version-info.xml" xpointer="v218"/></listitem>
</varlistentry>
<varlistentry>
<term><varname>T</varname></term>
<listitem><para>Same as <varname>t</varname>, but operates recursively.</para>
<xi:include href="version-info.xml" xpointer="v219"/></listitem>
</varlistentry>
<varlistentry>
<term><varname>h</varname></term>
<listitem><para>Set Linux 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>[+-=][aAcCdDeijPsStTu]</varname>. The prefix
<varname>+</varname> (the default one) causes the attributes to be added; <varname>-</varname>
causes the attributes to be removed; <varname>=</varname> causes the attributes to be set exactly
as the following letters. The letters <literal>aAcCdDeijPsStTu</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>
<para>Please note that the Linux file attributes settable with this line type are a different
concept from the extended attributes settable with <varname>t</varname>/<varname>T</varname>,
see above.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>H</varname></term>
<listitem><para>Sames as <varname>h</varname>, but operates recursively.</para>
<xi:include href="version-info.xml" xpointer="v220"/></listitem>
</varlistentry>
<varlistentry>
<term><varname>a</varname></term>
<term><varname>a+</varname></term>
<listitem><para>Set POSIX ACLs (access control lists), see
<citerefentry project='man-pages'><refentrytitle>acl</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
Additionally, if 'X' is used, the execute bit is set only if the file is a directory or already has
execute permission for some user, as mentioned in
<citerefentry project='man-pages'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
If suffixed with <varname>+</varname>, the specified entries will be added to the existing set.
<citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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>
<xi:include href="version-info.xml" xpointer="v219"/></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>
<xi:include href="version-info.xml" xpointer="v219"/></listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2>
<title>Type Modifiers</title>
<para>If the exclamation mark (<literal>!</literal>) is used, this line is only safe to 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.
<citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry>
will take lines with an exclamation mark only into consideration, if the <option>--boot</option> 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>
<para>If the minus sign (<literal>-</literal>) is used, this line failing to run successfully during
create (and only create) will not cause the execution of <command>systemd-tmpfiles</command> to return
an error.</para>
<para>For example:
<programlisting># Modify sysfs but don't fail if we are in a container with a read-only /proc
w- /proc/sys/vm/swappiness - - - - 10</programlisting></para>
<para>If the equals sign (<literal>=</literal>) is used, the file types of existing objects in the specified path
are checked, and removed if they do not match. This includes any implicitly created parent directories (which can
be either directories or directory symlinks). For example, if there is a FIFO in place of one of the parent path
components it will be replaced with a directory.</para>
<para>If the tilde character (<literal>~</literal>) is used, the argument (i.e. 6th) column is <ulink
url="https://www.rfc-editor.org/rfc/rfc4648.html">Base64 decoded</ulink> before use. This modifier is
only supported on line types that can write file contents, i.e. <varname>f</varname>,
<varname>f+</varname>, <varname>w</varname>, <varname>+</varname>. This is useful for writing arbitrary
binary data (including newlines and NUL bytes) to files. Note that if this switch is used, the argument
is not subject to specifier expansion, neither before nor after Base64 decoding.</para>
<para>If the caret character (<literal>^</literal>) is used, the argument (i.e. 6th) column takes a
service credential name to read the argument data from. See <ulink
url="https://systemd.io/CREDENTIALS">System and Service Credentials</ulink> for details about the
credentials concept. This modifier is only supported on line types that can write file contents,
i.e. <varname>f</varname>, <varname>f+</varname>, <varname>w</varname>, <varname>w+</varname>. This is
useful for writing arbitrary files with contents sourced from elsewhere, including from VM or container
managers further up. If the specified credential is not set for the <command>systemd-tmpfiles</command>
service, the line is silently skipped. If <literal>^</literal> and <literal>~</literal> are combined
Base64 decoding is applied to the credential contents.</para>
<para>Note that for all line types that result in creation of any kind of file node
(i.e. <varname>f</varname>,
<varname>d</varname>/<varname>D</varname>/<varname>v</varname>/<varname>q</varname>/<varname>Q</varname>,
<varname>p</varname>, <varname>L</varname>, <varname>c</varname>/<varname>b</varname> and <varname>C</varname>)
leading directories are implicitly created if needed, owned by root with an access mode of 0755. In order to
create them with different modes or ownership make sure to add appropriate <varname>d</varname> lines.</para>
</refsect2>
<refsect2>
<title>Path</title>
<para>The file system path specification supports simple
specifier expansion, see below. The path (after expansion) must be
absolute.</para>
</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>
<para>By default the access mode of listed inodes is set to the specified mode regardless if it is
created anew, or already existed. Optionally, if prefixed with <literal>:</literal>, the configured
access mode is only applied when creating new inodes, and if the inode the line refers to
already exists, its access mode is left in place unmodified.</para>
</refsect2>
<refsect2>
<title>User, Group</title>
<para>The user and group to use for this file or directory. This may either be a numeric ID or a
user/group name. If omitted or when set to <literal>-</literal>, the user and group of the user who
invokes
<citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry> 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>
<para>This field should generally only reference system users/groups, i.e. users/groups that are
guaranteed to be resolvable during early boot. If this field references users/groups that only become
resolveable during later boot (i.e. after NIS, LDAP or a similar networked directory service become
available), execution of the operations declared by the line will likely fail. Also see <ulink
url="https://systemd.io/UIDS-GIDS/#notes-on-resolvability-of-user-and-group-names">Notes on
Resolvability of User and Group Names</ulink> for more information on requirements on system user/group
definitions.</para>
<para>By default the ownership of listed inodes is set to the specified user/group regardless if it is
created anew, or already existed. Optionally, if prefixed with <literal>:</literal>, the configured
user/group information is only applied when creating new inodes, and if the inode the line refers to
already exists, its user/group is left in place unmodified.</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>, 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>
<para>The age of a file system entry is determined from its last
modification timestamp (mtime), its last access timestamp (atime),
and (except for directories) its last status change timestamp
(ctime). By default, any of these three (or two) values will
prevent cleanup if it is more recent than the current time minus
the age field. To restrict the deletion based on particular type
of file timestamps, the age-by argument can be used.</para>
<para>The age-by argument overrides the timestamp types to be used for the age check. It can be
specified by prefixing the age argument with a sequence of characters to specify the timestamp types
and a colon (<literal>:</literal>):
<literal><replaceable>age-by</replaceable>...:<replaceable>cleanup-age</replaceable></literal>. The
argument can consist of <constant>a</constant> (<constant>A</constant> for directories),
<constant>b</constant> (<constant>B</constant> for directories), <constant>c</constant>
(<constant>C</constant> for directories), or <constant>m</constant> (<constant>M</constant> for
directories). Those respectively indicate access, creation, last status change, and last modification
time of a file system entry. The lower-case letter signifies that the given timestamp type should be
considered for files, while the upper-case letter signifies that the given timestamp type should be
considered for directories. See <citerefentry
project='man-pages'><refentrytitle>statx</refentrytitle><manvolnum>2</manvolnum></citerefentry> file
timestamp fields for more details about timestamp types.</para>
<para>If not specified, the age-by field defaults to <constant>abcmABM</constant>, i.e. by default all
file timestamps are taken into consideration, with the exception of the last status change timestamp
(ctime) for directories. This is because the aging logic itself will alter the ctime whenever it
deletes a file inside it. To ensure that running the aging logic does not feed back into the next
iteration of itself, ctime for directories is ignored by default.</para>
<para>For example:<programlisting>
# Files created and modified, and directories accessed more than
# an hour ago in "/tmp/foo/bar", are subject to time-based cleanup.
d /tmp/foo/bar - - - bmA:1h -</programlisting></para>
<para>Note that while the aging algorithm is run an exclusive BSD file lock (see <citerefentry
project='man-pages'><refentrytitle>flock</refentrytitle><manvolnum>2</manvolnum></citerefentry>) is
taken on each directory/file the algorithm decides to remove. If the aging algorithm finds a lock
(shared or exclusive) is already taken on some directory/file, it (and everything below it) is skipped.
Applications may use this to temporarily exclude certain directory subtrees from the aging algorithm:
the applications can take a BSD file lock themselves, and as long as they keep it aging of the
directory/file and everything below it is disabled.</para>
<para>This behavior can be used to ensure guaranteed cleanup of files or directories whose lifetime
should be aligned with the process that created them by having that process create them in a location
monitored by <command>systemd-tmpfiles</command> with an age of <literal>0</literal>, and having the
process immediately lock the directory or file before using it. Because the BSD lock is process
specific, the file is guaranteed to be unlocked as soon as the process exits, meaning that even if the
process crashes, those files and directories will be unlocked and cleaned up by
<command>systemd-tmpfiles</command>.</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>
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>
<para>This field can contain specifiers, see below.</para>
</refsect2>
</refsect1>
<refsect1>
<title>Specifiers</title>
<para>Specifiers can be used in the "path" and "argument" fields.
An unknown or unresolvable specifier is treated as invalid configuration.
The following expansions are understood:</para>
<table class='specifiers'>
<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>
<xi:include href="standard-specifiers.xml" xpointer="a"/>
<xi:include href="standard-specifiers.xml" xpointer="A"/>
<xi:include href="standard-specifiers.xml" xpointer="b"/>
<xi:include href="standard-specifiers.xml" xpointer="B"/>
<row>
<entry><literal>%C</literal></entry>
<entry>System or user cache directory</entry>
<entry>In <option>--user</option> mode, this is the same as <varname>$XDG_CACHE_HOME</varname>, and <filename>/var/cache</filename> otherwise.</entry>
</row>
<row>
<entry><literal>%g</literal></entry>
<entry>User group</entry>
<entry>This is the name of the group running the command. In case of the system instance this resolves to <literal>root</literal>.</entry>
</row>
<row>
<entry><literal>%G</literal></entry>
<entry>User GID</entry>
<entry>This is the numeric GID of the group running the command. In case of the system instance this resolves to <constant>0</constant>.</entry>
</row>
<row>
<entry><literal>%h</literal></entry>
<entry>User home directory</entry>
<entry>This is the home directory of the user running the command. In case of the system instance this resolves to <literal>/root</literal>.</entry>
</row>
<xi:include href="standard-specifiers.xml" xpointer="H"/>
<xi:include href="standard-specifiers.xml" xpointer="l"/>
<row>
<entry><literal>%L</literal></entry>
<entry>System or user log directory</entry>
<entry>In <option>--user</option> mode, this is the same as <varname>$XDG_STATE_HOME</varname> with <filename index="false">/log</filename> appended, and <filename>/var/log</filename> otherwise.</entry>
</row>
<xi:include href="standard-specifiers.xml" xpointer="m"/>
<xi:include href="standard-specifiers.xml" xpointer="M"/>
<xi:include href="standard-specifiers.xml" xpointer="o"/>
<row>
<entry><literal>%S</literal></entry>
<entry>System or user state directory</entry>
<entry>In <option>--user</option> mode, this is the same as <varname>$XDG_STATE_HOME</varname>, and <filename>/var/lib</filename> otherwise.</entry>
</row>
<row>
<entry><literal>%t</literal></entry>
<entry>System or user runtime directory</entry>
<entry>In <option>--user</option> mode, this is the same <varname>$XDG_RUNTIME_DIR</varname>, and <filename>/run/</filename> otherwise.</entry>
</row>
<xi:include href="standard-specifiers.xml" xpointer="T"/>
<row>
<entry><literal>%u</literal></entry>
<entry>User name</entry>
<entry>This is the name of the user running the command. In case of the system instance this resolves to <literal>root</literal>.</entry>
</row>
<row>
<entry><literal>%U</literal></entry>
<entry>User UID</entry>
<entry>This is the numeric UID of the user running the command. In case of the system instance this resolves to <constant>0</constant>.</entry>
</row>
<xi:include href="standard-specifiers.xml" xpointer="v"/>
<xi:include href="standard-specifiers.xml" xpointer="V"/>
<xi:include href="standard-specifiers.xml" xpointer="w"/>
<xi:include href="standard-specifiers.xml" xpointer="W"/>
<xi:include href="standard-specifiers.xml" xpointer="percent"/>
</tbody>
</tgroup>
</table>
</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
be 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/cache/dnf/ - - - 30d
</programlisting>
<para>The lock files will be removed during boot. Any files and directories in
<filename>/var/cache/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>
<example>
<title>Provision SSH public key access for root user via Credentials in QEMU</title>
<programlisting>-smbios type=11,value=io.systemd.credential.binary:tmpfiles.extra=$(echo -e "d /root/.ssh 0750 root root -\nf~ /root/.ssh/authorized_keys 0600 root root - $(ssh-add -L | base64 -w 0)" | base64 -w 0)
</programlisting>
<para>By passing this line to QEMU, the public key of the current user will be encoded in base64, added
to a tmpfiles.d line that tells <command>systemd-tmpfiles</command> to decode it into
<filename>/root/.ssh/authorized_keys</filename>, encode that line itself in base64 and pass it as a
Credential that will be picked up by systemd from SMBIOS on boot.
</para>
</example>
</refsect1>
<refsect1>
<title><filename>/run/</filename> and <filename>/var/run/</filename></title>
<para><filename>/var/run/</filename> is a deprecated symlink to <filename>/run/</filename>, and
applications should use the latter. <command>systemd-tmpfiles</command> will warn if
<filename>/var/run/</filename> is used.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para><simplelist type="inline">
<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd-tmpfiles</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>attr</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>getfattr</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>setfattr</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>setfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>getfacl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry project='man-pages'><refentrytitle>chattr</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
<member><citerefentry project='url'><refentrytitle url='https://btrfs.readthedocs.io/en/latest/btrfs-subvolume.html'>btrfs-subvolume</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
<member><citerefentry project='url'><refentrytitle url='https://btrfs.readthedocs.io/en/latest/btrfs-qgroup.html'>btrfs-qgroup</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
</simplelist></para>
</refsect1>
</refentry>
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