Provided by: systemd_237-3ubuntu10.57_amd64 
NAME
sysusers.d - Declarative allocation of system users and groups
SYNOPSIS
/etc/sysusers.d/*.conf
/run/sysusers.d/*.conf
/usr/lib/sysusers.d/*.conf
DESCRIPTION
systemd-sysusers uses the files from sysusers.d directory to create system users and groups at package
installation or boot time. This tool may be used to allocate system users and groups only, it is not
useful for creating non-system (i.e. regular, "human") users and groups, as it accesses /etc/passwd and
/etc/group directly, bypassing any more complex user databases, for example any database involving NIS or
LDAP.
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/sysusers.d override files with the same name in /usr/lib/sysusers.d and /run/sysusers.d.
Files in /run/sysusers.d override files with the same name in /usr/lib/sysusers.d. Packages should
install their configuration files in /usr/lib/sysusers.d. Files in /etc/sysusers.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 later entries for the same user and group
names will be logged as warnings.
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/sysusers.d/ bearing the same filename.
CONFIGURATION FILE FORMAT
The file format is one line per user or group containing name, ID, GECOS field description and home
directory:
#Type Name ID GECOS Home directory
u httpd 440 "HTTP User"
u authd /usr/bin/authd "Authorization user"
g input - -
m authd input
u root 0 "Superuser" /root
Empty lines and lines beginning with the "#" character are ignored, and may be used for commenting.
Type
The type consists of a single letter. The following line types are understood:
u
Create a system user and group of the specified name should they not exist yet. The user's primary
group will be set to the group bearing the same name. The user's shell will be set to /sbin/nologin,
the home directory to the specified home directory, or / if none is given. The account will be
created disabled, so that logins are not allowed.
g
Create a system group of the specified name should it not exist yet. Note that u implicitly create a
matching group. The group will be created with no password set.
m
Add a user to a group. If the user or group do not exist yet, they will be implicitly created.
r
Add a range of numeric UIDs/GIDs to the pool to allocate new UIDs and GIDs from. If no line of this
type is specified, the range of UIDs/GIDs is set to some compiled-in default. Note that both UIDs and
GIDs are allocated from the same pool, in order to ensure that users and groups of the same name are
likely to carry the same numeric UID and GID.
Name
The name field specifies the user or group name. The specified name must consist only of the characters
a-z, A-Z, 0-9, "_" and "-", except for the first character which must be one of a-z, A-Z or "_" (i.e.
numbers and "-" are not permitted as first character). The user/group name must have at least one
character, and at most 31.
It is strongly recommended to pick user and group names that are unlikely to clash with normal users
created by the administrator. A good scheme to guarantee this is by prefixing all system and group names
with the underscore, and avoiding too generic names.
For m lines, this field should contain the user name to add to a group.
For lines of type r, this field should be set to "-".
ID
For u and g, the numeric 32-bit UID or GID of the user/group. Do not use IDs 65535 or 4294967295, as they
have special placeholder meanings. Specify "-" for automatic UID/GID allocation for the user or group.
Alternatively, specify an absolute path in the file system. In this case, the UID/GID is read from the
path's owner/group. This is useful to create users whose UID/GID match the owners of pre-existing files
(such as SUID or SGID binaries). The syntax "uid:gid" is also supported to allow creating user and group
pairs with different numeric UID and GID values. The group with the indicated GID must get created
explicitly before or it must already exist.
For m lines, this field should contain the group name to add to a user to.
For lines of type r, this field should be set to a UID/GID range in the format "FROM-TO", where both
values are formatted as decimal ASCII numbers. Alternatively, a single UID/GID may be specified formatted
as decimal ASCII numbers.
GECOS
A short, descriptive string for users to be created, enclosed in quotation marks. Note that this field
may not contain colons.
Only applies to lines of type u and should otherwise be left unset, or be set to "-".
Home Directory
The home directory for a new system user. If omitted, defaults to the root directory. It is recommended
to not unnecessarily specify home directories for system users, unless software strictly requires one to
be set.
Only applies to lines of type u and should otherwise be left unset, or be set to "-".
IDEMPOTENCE
Note that systemd-sysusers will do nothing if the specified users or groups already exist, so normally,
there is no reason to override sysusers.d vendor configuration, except to block certain users or groups
from being created.
SEE ALSO
systemd(1), systemd-sysusers(8)