Provided by: systemd_253.5-1ubuntu6.1_amd64 
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-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
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
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(8) uses this configuration to create volatile files and directories
during boot and to do periodic cleanup afterwards. See systemd-tmpfiles(8) for the
description of systemd-tmpfiles-setup.service, systemd-tmpfiles-clean.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. The lines are separated by newlines, the fields by whitespace:
#Type Path Mode User Group Age Argument...
d /run/user 0755 root root 10d -
L /tmp/foobar - - - - /dev/null
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.
"\x20").
Type
The type consists of a single letter and optionally one or more modifier characters: a
plus sign ("+"), exclamation mark ("!"), minus sign ("-"), equals sign ("="), tilde
character ("~") and/or caret ("^").
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. Contents of the directories are subject to time-based
cleanup if the age argument is specified.
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 attributes to be added; - causes the attributes 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.
Type Modifiers
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
If the equals sign ("=") 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.
If the tilde character ("~") is used, the argument (i.e. 6th) column is Base64 decoded[1]
before use. This modifier is only supported on line types that can write file contents,
i.e. f, f+, w, +. 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.
If the caret character ("^") is used, the argument (i.e. 6th) column takes a service
credential name to read the argument data from. See System and Service Credentials[2] for
details about the credentials concept. This modifier is only supported on line types that
can write file contents, i.e. f, f+, w, w+. 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 systemd-tmpfiles service, the line is
silently skipped. If "^" and "~" are combined Base64 decoding is applied to the credential
contents.
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.
Optionally, if prefixed with ":", the configured access mode is only used when creating
new inodes. If the inode the line refers to already exists, its access mode is left in
place unmodified.
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[3] for more
information on requirements on system user/group definitions.
Optionally, if prefixed with ":", the configured user/group information is only used when
creating new inodes. If the inode the line refers to already exists, its user/group is
left in place unmodified.
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 "~", 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). 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.
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 (":"): "age-by...:cleanup-age". The argument can consist of a
(A for directories), b (B for directories), c (C for directories), or m (M 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 statx(2) file timestamp
fields for more details about timestamp types.
If not specified, the age-by field defaults to abcmABM, 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.
For example:
# 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 -
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:
Table 1. Specifiers available
┌──────────┬──────────────────────────┬──────────────────────────┐
│Specifier │ Meaning │ Details │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%a" │ Architecture │ A short string │
│ │ │ identifying the │
│ │ │ architecture of the │
│ │ │ local system. A string │
│ │ │ such as x86, x86-64 or │
│ │ │ arm64. See the │
│ │ │ architectures defined │
│ │ │ for │
│ │ │ ConditionArchitecture= │
│ │ │ in systemd.unit(5) for a │
│ │ │ full list. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%A" │ Operating system image │ The operating system │
│ │ version │ image version identifier │
│ │ │ of the running system, │
│ │ │ as read from the │
│ │ │ IMAGE_VERSION= field of │
│ │ │ /etc/os-release. If not │
│ │ │ set, resolves to an │
│ │ │ empty string. See os- │
│ │ │ release(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%b" │ Boot ID │ The boot ID of the │
│ │ │ running system, │
│ │ │ formatted as string. See │
│ │ │ random(4) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%B" │ Operating system build │ The operating system │
│ │ ID │ build identifier of the │
│ │ │ running system, as read │
│ │ │ from the BUILD_ID= field │
│ │ │ of /etc/os-release. If │
│ │ │ not set, resolves to an │
│ │ │ empty string. See os- │
│ │ │ release(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%C" │ System or user cache │ In --user mode, this is │
│ │ directory │ the same as │
│ │ │ $XDG_CACHE_HOME, and │
│ │ │ /var/cache otherwise. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%g" │ User group │ This is the name of the │
│ │ │ group running the │
│ │ │ command. In case of the │
│ │ │ system instance this │
│ │ │ resolves to "root". │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%G" │ User GID │ This is the numeric GID │
│ │ │ of the group running the │
│ │ │ command. In case of the │
│ │ │ system instance this │
│ │ │ resolves to 0. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%h" │ User home directory │ This is the home │
│ │ │ directory of the user │
│ │ │ running the command. In │
│ │ │ case of the system │
│ │ │ instance this resolves │
│ │ │ to "/root". │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%H" │ Host name │ The hostname of the │
│ │ │ running system. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%l" │ Short host name │ The hostname of the │
│ │ │ running system, │
│ │ │ truncated at the first │
│ │ │ dot to remove any domain │
│ │ │ component. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%L" │ System or user log │ In --user mode, this is │
│ │ directory │ the same as │
│ │ │ $XDG_CONFIG_HOME with │
│ │ │ /log appended, and │
│ │ │ /var/log otherwise. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%m" │ Machine ID │ The machine ID of the │
│ │ │ running system, │
│ │ │ formatted as string. See │
│ │ │ machine-id(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%M" │ Operating system image │ The operating system │
│ │ identifier │ image identifier of the │
│ │ │ running system, as read │
│ │ │ from the IMAGE_ID= field │
│ │ │ of /etc/os-release. If │
│ │ │ not set, resolves to an │
│ │ │ empty string. See os- │
│ │ │ release(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%o" │ Operating system ID │ The operating system │
│ │ │ identifier of the │
│ │ │ running system, as read │
│ │ │ from the ID= field of │
│ │ │ /etc/os-release. See os- │
│ │ │ release(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%S" │ System or user state │ In --user mode, this is │
│ │ directory │ the same as │
│ │ │ $XDG_CONFIG_HOME, and │
│ │ │ /var/lib otherwise. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%t" │ System or user runtime │ In --user mode, this is │
│ │ directory │ the same │
│ │ │ $XDG_RUNTIME_DIR, and │
│ │ │ /run/ otherwise. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%T" │ Directory for temporary │ This is either /tmp or │
│ │ files │ the path "$TMPDIR", │
│ │ │ "$TEMP" or "$TMP" are │
│ │ │ set to. (Note that the │
│ │ │ directory may be │
│ │ │ specified without a │
│ │ │ trailing slash.) │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%u" │ User name │ This is the name of the │
│ │ │ user running the │
│ │ │ command. In case of the │
│ │ │ system instance this │
│ │ │ resolves to "root". │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%U" │ User UID │ This is the numeric UID │
│ │ │ of the user running the │
│ │ │ command. In case of the │
│ │ │ system instance this │
│ │ │ resolves to 0. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%v" │ Kernel release │ Identical to uname -r │
│ │ │ output. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%V" │ Directory for larger and │ This is either /var/tmp │
│ │ persistent temporary │ or the path "$TMPDIR", │
│ │ files │ "$TEMP" or "$TMP" are │
│ │ │ set to. (Note that the │
│ │ │ directory may be │
│ │ │ specified without a │
│ │ │ trailing slash.) │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%w" │ Operating system version │ The operating system │
│ │ ID │ version identifier of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ VERSION_ID= field of │
│ │ │ /etc/os-release. If not │
│ │ │ set, resolves to an │
│ │ │ empty string. See os- │
│ │ │ release(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%W" │ Operating system variant │ The operating system │
│ │ ID │ variant identifier of │
│ │ │ the running system, as │
│ │ │ read from the │
│ │ │ VARIANT_ID= field of │
│ │ │ /etc/os-release. If not │
│ │ │ set, resolves to an │
│ │ │ empty string. See os- │
│ │ │ release(5) for more │
│ │ │ information. │
├──────────┼──────────────────────────┼──────────────────────────┤
│"%%" │ Single percent sign │ Use "%%" in place of "%" │
│ │ │ to specify a single │
│ │ │ percent sign. │
└──────────┴──────────────────────────┴──────────────────────────┘
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 10½ 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.
Example 6. Provision SSH public key access for root user via Credentials in QEMU
-smbios type=11,value=io.systemd.credential.binary:tmpfiles.extra=$(echo "f~ /root/.ssh/authorized_keys 700 root root - $(ssh-add -L | base64 -w 0)" | base64 -w 0)
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 systemd-tmpfiles to decode it into
/root/.ssh/authorized_keys, encode that line itself in base64 and pass it as a Credential
that will be picked up by systemd from SMBIOS on boot.
/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. Base64 decoded
https://www.rfc-editor.org/rfc/rfc4648.html
2. System and Service Credentials
https://systemd.io/CREDENTIALS
3. Notes on Resolvability of User and Group Names
https://systemd.io/UIDS-GIDS/#notes-on-resolvability-of-user-and-group-names