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"    /path/to/shell
       u     user_name  uid:gid              -                     -
       u     user_name  /file/owned/by/user  -                     -
       g     group_name gid                  "Group Description"
       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.

   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.       │
       ├──────────┼─────────────────────┼────────────────────────┤
       │"%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.      │
       ├──────────┼─────────────────────┼────────────────────────┤
       │"%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.           │
       ├──────────┼─────────────────────┼────────────────────────┤
       │"%T"      │ Directory for       │ This is either /tmp or │
       │          │ temporary files     │ the path "$TMPDIR",    │
       │          │                     │ "$TEMP" or "$TMP" are  │
       │          │                     │ set to.                │
       ├──────────┼─────────────────────┼────────────────────────┤
       │"%v"      │ Kernel release      │ Identical to uname -r  │
       │          │                     │ output.                │
       ├──────────┼─────────────────────┼────────────────────────┤
       │"%V"      │ Directory for       │ This is either         │
       │          │ larger and          │ /var/tmp or the path   │
       │          │ persistent          │ "$TMPDIR", "$TEMP" or  │
       │          │ temporary files     │ "$TMP" are set to.     │
       ├──────────┼─────────────────────┼────────────────────────┤
       │"%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 sign │ Use "%%" in place of   │
       │          │                     │ "%" 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 2020-06-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-09.)  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 245                                                    SYSUSERS.D(5)

Pages that refer to this page: systemd.exec(5)30-systemd-environment-d-generator(7)systemd.directives(7)systemd.index(7)systemd-sysusers(8)systemd-sysusers.service(8)