Provided by: systemd_229-4ubuntu21.31_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
DESCRIPTION
systemd-tmpfiles uses the configuration files from the above directories to describe the
creation, cleaning and removal of volatile and temporary files and directories which
usually reside in directories such as /run or /tmp.
Volatile and temporary files and directories are those located in /run (and its alias
/var/run), /tmp, /var/tmp, the API file systems such as /sys or /proc, as well as some
other directories below /var.
System daemons frequently require private runtime directories below /run to place
communication sockets and similar in. For these, consider declaring them in their unit
files using RuntimeDirectory= (see systemd.exec(5) for details), if this is feasible.
CONFIGURATION FORMAT
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. All other
conflicting entries will be logged as errors. When two lines are prefix and suffix of each
other, then the prefix is always processed first, the suffix later. Lines that take globs
are applied after those accepting no globs. If multiple operations shall be applied on the
same file, (such as ACL, xattr, file attribute adjustments), these are always done in the
same fixed order. Otherwise, the files/directories are processed in the order they are
listed.
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.
The configuration format is one line per path containing type, path, mode, ownership, age,
and argument fields:
#Type Path Mode UID GID 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.
The following line types are understood:
f
Create a file if it does not exist yet. If the argument parameter is given, it will be
written to the file. Does not follow symlinks.
F
Create or truncate a file. If the argument parameter is given, it will be written to
the file. Does not follow symlinks.
w
Write the argument parameter to a file, if the file exists. Lines of this type accept
shell-style globs in place of normal path names. The argument parameter will be
written without a trailing newline. C-style backslash escapes are interpreted. Follows
symlinks.
d
Create a directory if it does not exist yet.
D
Create or empty a directory.
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
Similar to v. However, makes sure that the subvolume will be assigned to the same
higher-level quota groups as the subvolume it has been created in. This ensures that
higher-level limits and accounting applied to the parent subvolume also include the
specified subvolume. On non-btrfs file systems, this line type is identical to d. If
the subvolume already exists and is already assigned to one or more higher level quota
groups, no change to the quota hierarchy is made. Also see Q below. See btrfs-
qgroup(8) for details about the btrfs quota group concept.
Q
Similar to q. However, instead of copying the higher-level quota group assignments
from the parent as-is, the lowest quota group of the parent subvolume is determined
that is not the leaf quota group. Then, an "intermediary" quota group is inserted that
is one level below this level, and shares the same ID part as the specified subvolume.
If no higher-level quota group exists for the parent subvolume, a new quota group at
level 255 sharing the same ID as the specified subvolume is inserted instead. This new
intermediary quota group is then assigned to the parent subvolume's higher-level quota
groups, and the specified subvolume's leaf quota group is assigned to it.
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 exists and already has at least one
higher-level quota group assigned.
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 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. Note that this command will not descend into subdirectories if the
destination directory already exists. Instead, the entire copy operation is skipped.
If the argument is omitted, files from the source directory /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, group and user, and restore the SELinux security context of a
file or directory, if it exists. Lines of this type accept shell-style globs in place
of normal path names. Does not follow symlinks.
Z
Recursively set the access mode, group and user, and restore the SELinux security
context of a file or directory if it exists, as well as of its subdirectories and the
files contained therein (if applicable). Lines of this type accept shell-style globs
in place of normal path names. Does not follow symlinks.
t
Set extended attributes. Lines of this type accept shell-style globs in place of
normal path names. This can be useful for setting SMACK labels. Does not follow
symlinks.
T
Recursively set extended attributes. Lines of this type accept shell-style globs in
place of normal path names. This can be useful for setting SMACK labels. Does not
follow symlinks.
h
Set file/directory attributes. Lines of this type accept shell-style globs in place of
normal path names.
The format of the argument field is [+-=][aAcCdDeijsStTu] . 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
"aAcCdDeijsStTu" 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.
H
Recursively set file/directory attributes. Lines of this type accept shell-style globs
in place of normal path names. Does not follow symlinks.
a, a+
Set POSIX ACLs (access control lists). 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 of execute during boot, and can
break a running system. Lines without the exclamation mark are presumed to be safe to
execute at any time, e.g. on package upgrades. systemd-tmpfiles will execute line with an
exclamation mark only if option --boot 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.
Path
The file system path specification supports simple specifier expansion. The following
expansions are understood:
Table 1. Specifiers available
┌──────────┬────────────────┬──────────────────────────┐
│Specifier │ Meaning │ Details │
├──────────┼────────────────┼──────────────────────────┤
│"%m" │ Machine ID │ The machine ID of the │
│ │ │ running system, │
│ │ │ formatted as string. See │
│ │ │ machine-id(5) for more │
│ │ │ information. │
├──────────┼────────────────┼──────────────────────────┤
│"%b" │ Boot ID │ The boot ID of the │
│ │ │ running system, │
│ │ │ formatted as string. See │
│ │ │ random(4) for more │
│ │ │ information. │
├──────────┼────────────────┼──────────────────────────┤
│"%H" │ Host name │ The hostname of the │
│ │ │ running system. │
├──────────┼────────────────┼──────────────────────────┤
│"%v" │ Kernel release │ Identical to uname -r │
│ │ │ output. │
├──────────┼────────────────┼──────────────────────────┤
│"%%" │ Escaped % │ Single percent sign. │
└──────────┴────────────────┴──────────────────────────┘
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.
UID, GID
The user and group to use for this file or directory. This may either be a numeric
user/group ID or a user or group name. If omitted or when set to "-", the default 0 (root)
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.
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, 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.
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.
EXAMPLE
Example 1. /etc/tmpfiles.d/screen.conf example
screen needs two directories created at boot with specific modes and ownership.
d /run/screens 1777 root root 10d
d /run/uscreens 0755 root root 10d12h
t /run/screen - - - - user.name="John Smith" security.SMACK64=screen
Example 2. /etc/tmpfiles.d/abrt.conf example
abrt needs a directory created at boot with specific mode and ownership and its content
should be preserved.
d /var/tmp/abrt 0755 abrt abrt
x /var/tmp/abrt/*
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)