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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 all other conflicting entries logged as errors.

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

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.

F

Create or truncate a file. If the argument parameter is given, it will be written to the file.

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.

d

Create a directory if it does not exist yet.

D

Create or empty a directory.

p

Create a named pipe (FIFO) if it does not exist yet.

L

Create a symlink if it does not exist yet.

c

Create a character device node if it does not exist yet.

b

Create a block device node if it does not exist yet.

m

If the specified file path exists, adjust its access mode, group and user to the specified values and reset the SELinux security context. If it does not exist, do nothing.

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.

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.

z

Restore SELinux security context and set ownership and access mode of a file or directory if it exists. Lines of this type accept shell-style globs in place of normal path names.

Z

Recursively restore SELinux security context and set ownership and access mode of 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.

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

SpecifierMeaningDetails
"%m"Machine IDThe machine ID of the running system, formatted as string. See machine-id(5) for more information.
"%b"Boot IDThe boot ID of the running system, formatted as string. See random(4) for more information.
"%H"Host nameThe hostname of the running system.
"%v"Kernel releaseIdentical 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 lines.

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, Z lines, when omitted or when set to -, the file ownership will not be modified. These parameters are ignored for x, r, R, L 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 postfixes for the respective time units:

s, min, h, d, w, ms, m, us

If multiple integers and units are specified, the time values are summed up. 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, 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, 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 may be used to specify a short string that is written to the file, suffixed by a newline. 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

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)