sysusers.d

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



NAME
       sysusers.d - Declarative allocation of system users and groups

SYNOPSIS
       /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
       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
       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, 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
       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 "$TMP" are  │
       │          │                      │ set to. (Note that the │
       │          │                      │ directory may be       │
       │          │                      │ specified without a    │
       │          │                      │ trailing slash.)       │
       ├──────────┼──────────────────────┼────────────────────────┤
       │"%v"      │ Kernel release       │ Identical to uname -r  │
       │          │                      │ output.                │
       ├──────────┼──────────────────────┼────────────────────────┤
       │"%V"      │ Directory for larger │ This is either         │
       │          │ and persistent       │ /var/tmp or the path   │
       │          │ temporary files      │ "$TMPDIR", "$TEMP" or  │
       │          │                      │ "$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 sign  │ Use "%%" in place of   │
       │          │                      │ "%" to specify a       │
       │          │                      │ single percent sign.   │
       └──────────┴──────────────────────┴────────────────────────┘

IDEMPOTENCE
       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
       systemd(1), systemd-sysusers(8)

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



systemd 247                                                        SYSUSERS.D(5)