sysusers.d(5) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION DIRECTORIES AND PRECEDENCE | CONFIGURATION FILE FORMAT | SPECIFIERS | IDEMPOTENCE | SEE ALSO | NOTES | COLOPHON

SYSUSERS.D(5)                  sysusers.d                  SYSUSERS.D(5)

NAME         top

       sysusers.d - Declarative allocation of system users and groups

SYNOPSIS         top

       /etc/sysusers.d/*.conf

       /run/sysusers.d/*.conf

       /usr/lib/sysusers.d/*.conf

       #Type Name       ID                  GECOS              Home directory Shell
       u     user_name  uid                 "User Description" /home/dir      /path/to/shell
       u     user_name  uid:gid             "User Description" /home/dir      /path/to/shell
       u     user_name  /file/owned/by/user "User Description" /home/dir      /path/to/shell
       g     group_name gid
       g     group_name /file/owned/by/group
       m     user_name  group_name
       r     -          lowest-highest

DESCRIPTION         top

       systemd-sysusers uses the files from sysusers.d directory to
       create system users and groups and to add users to 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         top

       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         top

       The file format is one line per user or group containing name,
       ID, GECOS field description, home directory, and login shell:

           #Type Name     ID             GECOS                 Home directory Shell
           u     httpd    404            "HTTP User"
           u     _authd   /usr/bin/authd "Authorization user"
           u     postgres -              "Postgresql Database" /var/lib/pgsql /usr/libexec/postgresdb
           g     input    -              -
           m     _authd   input
           u     root     0              "Superuser"           /root          /bin/zsh
           r     -        500-900

       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 unless the ID field specifies
           it. 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 creates 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.

       For further details about the syntax of user/group names, see
       User/Group Name Syntax[1].

       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 (this is strongly recommended unless it is strictly
       necessary to use a specific UID or GID). 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 syntaxes "uid:gid" and
       "uid:groupname" are supported to allow creating users with
       specific primary groups. The given group must be created
       explicitly, or it must already exist. Specifying "-" for the UID
       in these syntaxes is also supported.

       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 "-").

   Home Directory
       The home directory for a new system user. If omitted, defaults to
       the root directory.

       Only applies to lines of type u and should otherwise be left
       unset (or "-"). It is recommended to omit this, unless software
       strictly requires a home directory to be set.

       systemd-sysusers only sets the home directory record in the user
       database. To actually create the directory, consider adding a
       corresponding tmpfiles.d(5) fragment.

   Shell
       The login shell of the user. If not specified, this will be set
       to /usr/sbin/nologin, except if the UID of the user is 0, in
       which case /bin/sh will be used.

       Only applies to lines of type u and should otherwise be left
       unset (or "-"). It is recommended to omit this, unless a shell
       different /usr/sbin/nologin must be used.

SPECIFIERS         top

       Specifiers can be used in the "Name", "ID", "GECOS", "Home
       directory", and "Shell" 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 │ The operating system   │
       │          │ image 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 │ The operating system   │
       │          │ build 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.           │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%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.      │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%m"      │ Machine ID       │ The machine ID of the  │
       │          │                  │ running system,        │
       │          │                  │ formatted as string.   │
       │          │                  │ See machine-id(5) for  │
       │          │                  │ more information.      │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%M"      │ Operating system │ The operating system   │
       │          │ image 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 │ The operating system   │
       │          │ ID               │ identifier of the      │
       │          │                  │ running system, as     │
       │          │                  │ read from the ID=      │
       │          │                  │ field of               │
       │          │                  │ /etc/os-release. See   │
       │          │                  │ os-release(5) for more │
       │          │                  │ information.           │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%T"      │ Directory for    │ This is either /tmp or │
       │          │ temporary files  │ the path "$TMPDIR",    │
       │          │                  │ "$TEMP" or "$TMP" are  │
       │          │                  │ set to. (Note that the │
       │          │                  │ directory may be       │
       │          │                  │ specified without a    │
       │          │                  │ trailing slash.)       │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%v"      │ Kernel release   │ Identical to uname -r  │
       │          │                  │ output.                │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%V"      │ Directory for    │ This is either         │
       │          │ larger and       │ /var/tmp or the path   │
       │          │ persistent       │ "$TMPDIR", "$TEMP" or  │
       │          │ temporary files  │ "$TMP" are set to.     │
       │          │                  │ (Note that the         │
       │          │                  │ directory may be       │
       │          │                  │ specified without a    │
       │          │                  │ trailing slash.)       │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%w"      │ Operating system │ The operating system   │
       │          │ version 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 │ The operating system   │
       │          │ variant 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   │ Use "%%" in place of   │
       │          │ sign             │ "%" to specify a       │
       │          │                  │ single percent sign.   │
       └──────────┴──────────────────┴────────────────────────┘

IDEMPOTENCE         top

       Note that systemd-sysusers will do nothing if the specified users
       or groups already exist or the users are members of specified
       groups, so normally there is no reason to override sysusers.d
       vendor configuration, except to block certain users or groups
       from being created.

SEE ALSO         top

       systemd(1), systemd-sysusers(8)

NOTES         top

        1. User/Group Name Syntax
           https://systemd.io/USER_NAMES

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-27.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                                                SYSUSERS.D(5)

Pages that refer to this page: systemd.exec(5)systemd-sysusers(8)