tmpfiles.d(5)

TMPFILES.D(5) tmpfiles.d TMPFILES.D(5)

NAME
tmpfiles.d - Configuration for creation, deletion and cleaning of
volatile and temporary files

SYNOPSIS
/etc/tmpfiles.d/*.conf
/run/tmpfiles.d/*.conf
/usr/lib/tmpfiles.d/*.conf

~/.config/user-tmpfiles.d/*.conf
$XDG_RUNTIME_DIR/user-tmpfiles.d/*.conf
~/.local/share/user-tmpfiles.d/*.conf
...
/usr/share/user-tmpfiles.d/*.conf

#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-cleanup mode user group cleanup-age -
D /directory/to/create-and-remove mode user group cleanup-age -
e /directory/to/cleanup mode user group cleanup-age -
v /subvolume-or-directory/to/create mode user group - -
q /subvolume-or-directory/to/create mode user group - -
Q /subvolume-or-directory/to/create mode user group - -
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 - - - - /source/to/copy
x /path-or-glob/to/ignore - - - - -
X /path-or-glob/to/ignore/recursively - - - - -
r /empty/dir/to/remove - - - - -
R /dir/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

DESCRIPTION
tmpfiles.d configuration files provide a generic mechanism to define
the creation of regular files, directories, pipes, and device nodes,
adjustments to their access mode, ownership, attributes, quota
assignments, and contents, and finally their time-based removal. It is
mostly commonly used for volatile and temporary files and directories
(such as those located under /run, /tmp, /var/tmp, the API file systems
such as /sys or /proc, as well as some other directories below /var).

systemd-tmpfiles uses this configuration to create volatile files and
directories during boot and to do periodic cleanup afterwards. See
systemd-tmpfiles(5) for the description of
systemd-tmpfiles-setup.service, systemd-tmpfiles-cleanup.service, and
associated units.

System daemons frequently require private runtime directories below
/run to store communication sockets and similar. For these, it is
better to use RuntimeDirectory= in their unit files (see
systemd.exec(5) for details), if the flexibility provided by tmpfiles.d
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,
StateDirectory=, CacheDirectory=, LogsDirectory=, and
ConfigurationDirectory= should be used to create directories under
/var/lib/, /var/cache/, /var/log/, and /etc/. tmpfiles.d should be
used for files whose lifetime is independent of any service or requires
more complicated configuration.

CONFIGURATION DIRECTORIES AND PRECEDENCE
Each configuration file shall be named in the style of package.conf or
package-part.conf. The second variant should be used when it is
desirable to make it easy to override just this part of configuration.

Files in /etc/tmpfiles.d override files with the same name in
/usr/lib/tmpfiles.d and /run/tmpfiles.d. Files in /run/tmpfiles.d
override files with the same name in /usr/lib/tmpfiles.d. Packages
should install their configuration files in /usr/lib/tmpfiles.d. Files
in /etc/tmpfiles.d 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 "!" 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.

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

CONFIGURATION FILE FORMAT
The configuration format is one line per path containing type, path,
mode, ownership, age, and argument fields:

#Type Path Mode User Group Age Argument
d /run/user 0755 root root 10d -
L /tmp/foobar - - - - /dev/null

Fields may be enclosed within quotes and contain C-style escapes.

Type
The type consists of a single letter and optionally an exclamation mark
("!") and/or minus sign ("-").

The following line types are understood:

f, f+
f 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. f+ will create or truncate the file. If the
argument parameter is given, it will be written to the file. Does
not follow symlinks.

w, w+
Write the argument parameter to a file, if the file exists. If
suffixed with +, the line will be appended to the file. If your
configuration writes multiple lines to the same file, use w+. 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.

d
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.

D
Similar to d, but in addition the contents of the directory will be
removed when --remove is used.

e
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 "0", contents will be unconditionally
deleted every time systemd-tmpfiles --clean is run.

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 !, see the examples.

v
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 / is itself a
subvolume). Otherwise, create a normal directory, in the same way
as d.

A subvolume created with this line type is not assigned to any
higher-level quota group. For that, use q or Q, which allow
creating simple quota group hierarchies, see below.

q
Create a subvolume or directory the same as v, 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 d.

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 Q below. See btrfs-qgroup(8) for
details about the btrfs quota group concept.

Q
Create the subvolume or directory the same as v, 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 q, 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.

Effectively, this has a similar effect as q, 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 q and Q, a concept of "subtree quotas" is
implemented. Each subvolume for which Q 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 q 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.

It is recommended to use Q 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 Q
are typically /home or /var/lib/machines. In contrast, q 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 q are
typically /var or /var/tmp.

As with q, Q 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.

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

L, L+
Create a symlink if it does not exist yet. If suffixed with + 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 /usr/share/factory/ are created. Note that
permissions and ownership on symlinks are ignored.

c, c+
Create a character device node if it does not exist yet. If
suffixed with + 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.

b, b+
Create a block device node if it does not exist yet. If suffixed
with + 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.

C
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. Instead, the
entire copy operation is skipped. If the argument is omitted, files
from the source directory /usr/share/factory/ with the same name
are copied. Does not follow symlinks.

x
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 r or R lines. Lines of
this type accept shell-style globs in place of normal path names.

X
Ignore a path during cleaning. Use this type to exclude paths from
clean-up as controlled with the Age parameter. Unlike x, 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 r or R lines. Lines of this type accept
shell-style globs in place of normal path names.

r
Remove a file or directory if it exists. This may not be used to
remove non-empty directories, use R for that. Lines of this type
accept shell-style globs in place of normal path names. Does not
follow symlinks.

R
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.

z
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.

Z
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.

t
Set extended attributes, see attr(5) for details. The argument
field should take one or more assignment expressions in the form
namespace.attribute=value, 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.

Please note that extended attributes settable with this line type
are a different concept from the Linux file attributes settable
with h/H, see below.

T
Same as t, but operates recursively.

h
Set Linux file/directory attributes. Lines of this type accept
shell-style globs in place of normal path names.

The format of the argument field is [+-=][aAcCdDeijPsStTu]. The
prefix + (the default one) causes the attribute(s) to be added; -
causes the attribute(s) to be removed; = causes the attributes to
be set exactly as the following letters. The letters
"aAcCdDeijPsStTu" select the new attributes for the files, see
chattr(1) for further information.

Passing only = as argument resets all the file attributes listed
above. It has to be pointed out that the = prefix limits itself to
the attributes corresponding to the letters listed here. All other
attributes will be left untouched. Does not follow symlinks.

Please note that the Linux file attributes settable with this line
type are a different concept from the extended attributes settable
with t/T, see above.

H
Sames as h, but operates recursively.

a, a+
Set POSIX ACLs (access control lists), see acl(5). If suffixed with
+, the specified entries will be added to the existing set.
systemd-tmpfiles 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.

A, A+
Same as a and a+, but recursive. Does not follow symlinks.

If the exclamation mark ("!") 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. systemd-tmpfiles will take lines with an
exclamation mark only into consideration, if the --boot option is
given.

For example:

# 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

The second line in contrast to the first one would break a running
system, and will only be executed with --boot.

If the minus sign ("-") is used, this line failing to run successfully
during create (and only create) will not cause the execution of
systemd-tmpfiles to return an error.

For example:

# Modify sysfs but don't fail if we are in a container with a read-only /proc
w- /proc/sys/vm/swappiness - - - - 10

Note that for all line types that result in creation of any kind of
file node (i.e. f/F, d/D/v/q/Q, p, L, c/b and C) 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 d lines.

Path
The file system path specification supports simple specifier expansion,
see below. The path (after expansion) must be absolute.

Mode
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 z, Z lines, if omitted or when set
to "-", the file access mode will not be modified. This parameter is
ignored for x, r, R, L, t, and a lines.

Optionally, if prefixed with "~", 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 Z.

User, Group
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 "-",
the user and group of the user who invokes systemd-tmpfiles is used.
For z and Z lines, when omitted or when set to "-", the file ownership
will not be modified. These parameters are ignored for x, r, R, L, t,
and a lines.

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 Notes on Resolvability of User and
Group Names[1] for more information on requirements on system
user/group definitions.

Age
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: s, m or min, h, d, w, ms, and us, meaning seconds, minutes,
hours, days, weeks, milliseconds, and microseconds, respectively. Full
names of the time units can be used too.

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

When the age is set to zero, the files are cleaned unconditionally.

The age field only applies to lines starting with d, D, e, v, q, Q, C,
x and X. If omitted or set to "-", no automatic clean-up is done.

If the age field starts with a tilde character "~", 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.

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). Any of these
three (or two) values will prevent cleanup if it is more recent than
the current time minus the age field.

Note that while the aging algorithm is run a 'shared' BSD file lock
(see flock(2)) is taken on each directory the algorithm descends into
(and each directory below that, and so on). If the aging algorithm
finds a lock is already taken on some directory, 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 and everything below it is disabled.

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

This field can contain specifiers, see below.

SPECIFIERS
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:

EXAMPLES
Example 1. Create directories with specific mode and ownership

screen(1), needs two directories created at boot with specific modes
and ownership:

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

Contents of /run/screens and /run/uscreens will be cleaned up after 10
and 101/2 days, respectively.

Example 2. Create a directory with a SMACK attribute

D /run/cups - - - -
t /run/cups - - - - security.SMACK64=printing user.attr-with-spaces="foo bar"

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
systemd-tmpfiles --remove runs.

Example 3. Create a directory and prevent its contents from cleanup

abrt(1), 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 /var/tmp:

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

# /usr/lib/tmpfiles.d/abrt.conf
d /var/tmp/abrt 0755 abrt abrt -

Example 4. Apply clean up during boot and based on time

# /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

The lock files will be removed during boot. Any files and directories
in /var/cache/dnf/ will be removed after they have not been accessed in
30 days.

Example 5. Empty the contents of a cache directory on boot

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

Any files and subdirectories in /var/cache/krb5rcache/ will be removed
on boot. The directory will not be created.

/RUN/ AND /VAR/RUN/
/var/run/ is a deprecated symlink to /run/, and applications should use
the latter. systemd-tmpfiles will warn if /var/run/ is used.

SEE ALSO
systemd(1), systemd-tmpfiles(8), systemd-delta(1), systemd.exec(5),
attr(5), getfattr(1), setfattr(1), setfacl(1), getfacl(1), chattr(1),
btrfs-subvolume(8), btrfs-qgroup(8)

NOTES
1. Notes on Resolvability of User and Group Names
https://systemd.io/UIDS-GIDS/#notes-on-resolvability-of-user-and-group-names

systemd 245 TMPFILES.D(5)

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