path: root/man/man8/useradd.8

'\" t
.\"     Title: useradd
.\"    Author: Julianne Frances Haugh
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 12/01/2019
.\"    Manual: System Management Commands
.\"    Source: shadow-utils 4.8
.\"  Language: English
.\"
.TH "USERADD" "8" "12/01/2019" "shadow\-utils 4\&.8" "System Management Commands"
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.SH "NAME"
useradd \- create a new user or update default new user information
.SH "SYNOPSIS"
.HP \w'\fBuseradd\fR\ 'u
\fBuseradd\fR [\fIoptions\fR] \fILOGIN\fR
.HP \w'\fBuseradd\fR\ 'u
\fBuseradd\fR \-D
.HP \w'\fBuseradd\fR\ 'u
\fBuseradd\fR \-D [\fIoptions\fR]
.SH "DESCRIPTION"
.PP
When invoked without the
\fB\-D\fR
option, the
\fBuseradd\fR
command creates a new user account using the values specified on the command line plus the default values from the system\&. Depending on command line options, the
\fBuseradd\fR
command will update system files and may also create the new user\*(Aqs home directory and copy initial files\&.
.PP
By default, a group will also be created for the new user (see
\fB\-g\fR,
\fB\-N\fR,
\fB\-U\fR, and
\fBUSERGROUPS_ENAB\fR)\&.
.SH "OPTIONS"
.PP
The options which apply to the
\fBuseradd\fR
command are:
.PP
\fB\-\-badname\fR\ \&
.RS 4
Allow names that do not conform to standards\&.
.RE
.PP
\fB\-b\fR, \fB\-\-base\-dir\fR\ \&\fIBASE_DIR\fR
.RS 4
The default base directory for the system if
\fB\-d\fR\ \&\fIHOME_DIR\fR
is not specified\&.
\fIBASE_DIR\fR
is concatenated with the account name to define the home directory\&. If the
\fB\-m\fR
option is not used,
\fIBASE_DIR\fR
must exist\&.
.sp
If this option is not specified,
\fBuseradd\fR
will use the base directory specified by the
\fBHOME\fR
variable in
/etc/default/useradd, or
/home
by default\&.
.RE
.PP
\fB\-c\fR, \fB\-\-comment\fR\ \&\fICOMMENT\fR
.RS 4
Any text string\&. It is generally a short description of the login, and is currently used as the field for the user\*(Aqs full name\&.
.RE
.PP
\fB\-d\fR, \fB\-\-home\-dir\fR\ \&\fIHOME_DIR\fR
.RS 4
The new user will be created using
\fIHOME_DIR\fR
as the value for the user\*(Aqs login directory\&. The default is to append the
\fILOGIN\fR
name to
\fIBASE_DIR\fR
and use that as the login directory name\&. The directory
\fIHOME_DIR\fR
does not have to exist but will not be created if it is missing\&.
.RE
.PP
\fB\-D\fR, \fB\-\-defaults\fR
.RS 4
See below, the subsection "Changing the default values"\&.
.RE
.PP
\fB\-e\fR, \fB\-\-expiredate\fR\ \&\fIEXPIRE_DATE\fR
.RS 4
The date on which the user account will be disabled\&. The date is specified in the format
\fIYYYY\-MM\-DD\fR\&.
.sp
If not specified,
\fBuseradd\fR
will use the default expiry date specified by the
\fBEXPIRE\fR
variable in
/etc/default/useradd, or an empty string (no expiry) by default\&.
.RE
.PP
\fB\-f\fR, \fB\-\-inactive\fR\ \&\fIINACTIVE\fR
.RS 4
The number of days after a password expires until the account is permanently disabled\&. A value of 0 disables the account as soon as the password has expired, and a value of \-1 disables the feature\&.
.sp
If not specified,
\fBuseradd\fR
will use the default inactivity period specified by the
\fBINACTIVE\fR
variable in
/etc/default/useradd, or \-1 by default\&.
.RE
.PP
\fB\-g\fR, \fB\-\-gid\fR\ \&\fIGROUP\fR
.RS 4
The group name or number of the user\*(Aqs initial login group\&. The group name must exist\&. A group number must refer to an already existing group\&.
.sp
If not specified, the behavior of
\fBuseradd\fR
will depend on the
\fBUSERGROUPS_ENAB\fR
variable in
/etc/login\&.defs\&. If this variable is set to
\fIyes\fR
(or
\fB\-U/\-\-user\-group\fR
is specified on the command line), a group will be created for the user, with the same name as her loginname\&. If the variable is set to
\fIno\fR
(or
\fB\-N/\-\-no\-user\-group\fR
is specified on the command line), useradd will set the primary group of the new user to the value specified by the
\fBGROUP\fR
variable in
/etc/default/useradd, or 100 by default\&.
.RE
.PP
\fB\-G\fR, \fB\-\-groups\fR\ \&\fIGROUP1\fR[\fI,GROUP2,\&.\&.\&.\fR[\fI,GROUPN\fR]]]
.RS 4
A list of supplementary groups which the user is also a member of\&. Each group is separated from the next by a comma, with no intervening whitespace\&. The groups are subject to the same restrictions as the group given with the
\fB\-g\fR
option\&. The default is for the user to belong only to the initial group\&.
.RE
.PP
\fB\-h\fR, \fB\-\-help\fR
.RS 4
Display help message and exit\&.
.RE
.PP
\fB\-k\fR, \fB\-\-skel\fR\ \&\fISKEL_DIR\fR
.RS 4
The skeleton directory, which contains files and directories to be copied in the user\*(Aqs home directory, when the home directory is created by
\fBuseradd\fR\&.
.sp
This option is only valid if the
\fB\-m\fR
(or
\fB\-\-create\-home\fR) option is specified\&.
.sp
If this option is not set, the skeleton directory is defined by the
\fBSKEL\fR
variable in
/etc/default/useradd
or, by default,
/etc/skel\&.
.sp
If possible, the ACLs and extended attributes are copied\&.
.RE
.PP
\fB\-K\fR, \fB\-\-key\fR\ \&\fIKEY\fR=\fIVALUE\fR
.RS 4
Overrides
/etc/login\&.defs
defaults (\fBUID_MIN\fR,
\fBUID_MAX\fR,
\fBUMASK\fR,
\fBPASS_MAX_DAYS\fR
and others)\&.

Example:
\fB\-K\fR\ \&\fIPASS_MAX_DAYS\fR=\fI\-1\fR
can be used when creating system account to turn off password aging, even though system account has no password at all\&. Multiple
\fB\-K\fR
options can be specified, e\&.g\&.:
\fB\-K\fR\ \&\fIUID_MIN\fR=\fI100\fR\ \&
\fB\-K\fR\ \&\fIUID_MAX\fR=\fI499\fR
.RE
.PP
\fB\-l\fR, \fB\-\-no\-log\-init\fR
.RS 4
Do not add the user to the lastlog and faillog databases\&.
.sp
By default, the user\*(Aqs entries in the lastlog and faillog databases are reset to avoid reusing the entry from a previously deleted user\&.
.RE
.PP
\fB\-m\fR, \fB\-\-create\-home\fR
.RS 4
Create the user\*(Aqs home directory if it does not exist\&. The files and directories contained in the skeleton directory (which can be defined with the
\fB\-k\fR
option) will be copied to the home directory\&.
.sp
By default, if this option is not specified and
\fBCREATE_HOME\fR
is not enabled, no home directories are created\&.
.RE
.PP
\fB\-M\fR, \fB\-\-no\-create\-home\fR
.RS 4
Do no create the user\*(Aqs home directory, even if the system wide setting from
/etc/login\&.defs
(\fBCREATE_HOME\fR) is set to
\fIyes\fR\&.
.RE
.PP
\fB\-N\fR, \fB\-\-no\-user\-group\fR
.RS 4
Do not create a group with the same name as the user, but add the user to the group specified by the
\fB\-g\fR
option or by the
\fBGROUP\fR
variable in
/etc/default/useradd\&.
.sp
The default behavior (if the
\fB\-g\fR,
\fB\-N\fR, and
\fB\-U\fR
options are not specified) is defined by the
\fBUSERGROUPS_ENAB\fR
variable in
/etc/login\&.defs\&.
.RE
.PP
\fB\-o\fR, \fB\-\-non\-unique\fR
.RS 4
Allow the creation of a user account with a duplicate (non\-unique) UID\&.
.sp
This option is only valid in combination with the
\fB\-u\fR
option\&.
.RE
.PP
\fB\-p\fR, \fB\-\-password\fR\ \&\fIPASSWORD\fR
.RS 4
The encrypted password, as returned by
\fBcrypt\fR(3)\&. The default is to disable the password\&.
.sp
\fBNote:\fR
This option is not recommended because the password (or encrypted password) will be visible by users listing the processes\&.
.sp
You should make sure the password respects the system\*(Aqs password policy\&.
.RE
.PP
\fB\-r\fR, \fB\-\-system\fR
.RS 4
Create a system account\&.
.sp
System users will be created with no aging information in
/etc/shadow, and their numeric identifiers are chosen in the
\fBSYS_UID_MIN\fR\-\fBSYS_UID_MAX\fR
range, defined in
/etc/login\&.defs, instead of
\fBUID_MIN\fR\-\fBUID_MAX\fR
(and their
\fBGID\fR
counterparts for the creation of groups)\&.
.sp
Note that
\fBuseradd\fR
will not create a home directory for such a user, regardless of the default setting in
/etc/login\&.defs
(\fBCREATE_HOME\fR)\&. You have to specify the
\fB\-m\fR
options if you want a home directory for a system account to be created\&.
.RE
.PP
\fB\-R\fR, \fB\-\-root\fR\ \&\fICHROOT_DIR\fR
.RS 4
Apply changes in the
\fICHROOT_DIR\fR
directory and use the configuration files from the
\fICHROOT_DIR\fR
directory\&.
.RE
.PP
\fB\-P\fR, \fB\-\-prefix\fR\ \&\fIPREFIX_DIR\fR
.RS 4
Apply changes in the
\fIPREFIX_DIR\fR
directory and use the configuration files from the
\fIPREFIX_DIR\fR
directory\&. This option does not chroot and is intended for preparing a cross\-compilation target\&. Some limitations: NIS and LDAP users/groups are not verified\&. PAM authentication is using the host files\&. No SELINUX support\&.
.RE
.PP
\fB\-s\fR, \fB\-\-shell\fR\ \&\fISHELL\fR
.RS 4
The name of the user\*(Aqs login shell\&. The default is to leave this field blank, which causes the system to select the default login shell specified by the
\fBSHELL\fR
variable in
/etc/default/useradd, or an empty string by default\&.
.RE
.PP
\fB\-u\fR, \fB\-\-uid\fR\ \&\fIUID\fR
.RS 4
The numerical value of the user\*(Aqs ID\&. This value must be unique, unless the
\fB\-o\fR
option is used\&. The value must be non\-negative\&. The default is to use the smallest ID value greater than or equal to
\fBUID_MIN\fR
and greater than every other user\&.
.sp
See also the
\fB\-r\fR
option and the
\fBUID_MAX\fR
description\&.
.RE
.PP
\fB\-U\fR, \fB\-\-user\-group\fR
.RS 4
Create a group with the same name as the user, and add the user to this group\&.
.sp
The default behavior (if the
\fB\-g\fR,
\fB\-N\fR, and
\fB\-U\fR
options are not specified) is defined by the
\fBUSERGROUPS_ENAB\fR
variable in
/etc/login\&.defs\&.
.RE
.PP
\fB\-Z\fR, \fB\-\-selinux\-user\fR\ \&\fISEUSER\fR
.RS 4
The SELinux user for the user\*(Aqs login\&. The default is to leave this field blank, which causes the system to select the default SELinux user\&.
.RE
.SS "Changing the default values"
.PP
When invoked with only the
\fB\-D\fR
option,
\fBuseradd\fR
will display the current default values\&. When invoked with
\fB\-D\fR
plus other options,
\fBuseradd\fR
will update the default values for the specified options\&. Valid default\-changing options are:
.PP
\fB\-b\fR, \fB\-\-base\-dir\fR\ \&\fIBASE_DIR\fR
.RS 4
The path prefix for a new user\*(Aqs home directory\&. The user\*(Aqs name will be affixed to the end of
\fIBASE_DIR\fR
to form the new user\*(Aqs home directory name, if the
\fB\-d\fR
option is not used when creating a new account\&.
.sp
This option sets the
\fBHOME\fR
variable in
/etc/default/useradd\&.
.RE
.PP
\fB\-e\fR, \fB\-\-expiredate\fR\ \&\fIEXPIRE_DATE\fR
.RS 4
The date on which the user account is disabled\&.
.sp
This option sets the
\fBEXPIRE\fR
variable in
/etc/default/useradd\&.
.RE
.PP
\fB\-f\fR, \fB\-\-inactive\fR\ \&\fIINACTIVE\fR
.RS 4
The number of days after a password has expired before the account will be disabled\&.
.sp
This option sets the
\fBINACTIVE\fR
variable in
/etc/default/useradd\&.
.RE
.PP
\fB\-g\fR, \fB\-\-gid\fR\ \&\fIGROUP\fR
.RS 4
The group name or ID for a new user\*(Aqs initial group (when the
\fB\-N/\-\-no\-user\-group\fR
is used or when the
\fBUSERGROUPS_ENAB\fR
variable is set to
\fIno\fR
in
/etc/login\&.defs)\&. The named group must exist, and a numerical group ID must have an existing entry\&.
.sp
This option sets the
\fBGROUP\fR
variable in
/etc/default/useradd\&.
.RE
.PP
\fB\-s\fR, \fB\-\-shell\fR\ \&\fISHELL\fR
.RS 4
The name of a new user\*(Aqs login shell\&.
.sp
This option sets the
\fBSHELL\fR
variable in
/etc/default/useradd\&.
.RE
.SH "NOTES"
.PP
The system administrator is responsible for placing the default user files in the
/etc/skel/
directory (or any other skeleton directory specified in
/etc/default/useradd
or on the command line)\&.
.SH "CAVEATS"
.PP
You may not add a user to a NIS or LDAP group\&. This must be performed on the corresponding server\&.
.PP
Similarly, if the username already exists in an external user database such as NIS or LDAP,
\fBuseradd\fR
will deny the user account creation request\&.
.PP
Usernames must start with a lower case letter or an underscore, followed by lower case letters, digits, underscores, or dashes\&. They can end with a dollar sign\&. In regular expression terms: [a\-z_][a\-z0\-9_\-]*[$]?
.PP
Usernames may only be up to 32 characters long\&.
.SH "CONFIGURATION"
.PP
The following configuration variables in
/etc/login\&.defs
change the behavior of this tool:
.PP
\fBCREATE_HOME\fR (boolean)
.RS 4
Indicate if a home directory should be created by default for new users\&.
.sp
This setting does not apply to system users, and can be overridden on the command line\&.
.RE
.PP
\fBGID_MAX\fR (number), \fBGID_MIN\fR (number)
.RS 4
Range of group IDs used for the creation of regular groups by
\fBuseradd\fR,
\fBgroupadd\fR, or
\fBnewusers\fR\&.
.sp
The default value for
\fBGID_MIN\fR
(resp\&.
\fBGID_MAX\fR) is 1000 (resp\&. 60000)\&.
.RE
.PP
\fBLASTLOG_UID_MAX\fR (number)
.RS 4
Highest user ID number for which the lastlog entries should be updated\&. As higher user IDs are usually tracked by remote user identity and authentication services there is no need to create a huge sparse lastlog file for them\&.
.sp
No
\fBLASTLOG_UID_MAX\fR
option present in the configuration means that there is no user ID limit for writing lastlog entries\&.
.RE
.PP
\fBMAIL_DIR\fR (string)
.RS 4
The mail spool directory\&. This is needed to manipulate the mailbox when its corresponding user account is modified or deleted\&. If not specified, a compile\-time default is used\&.
.RE
.PP
\fBMAIL_FILE\fR (string)
.RS 4
Defines the location of the users mail spool files relatively to their home directory\&.
.RE
.PP
The
\fBMAIL_DIR\fR
and
\fBMAIL_FILE\fR
variables are used by
\fBuseradd\fR,
\fBusermod\fR, and
\fBuserdel\fR
to create, move, or delete the user\*(Aqs mail spool\&.
.PP
If
\fBMAIL_CHECK_ENAB\fR
is set to
\fIyes\fR, they are also used to define the
\fBMAIL\fR
environment variable\&.
.PP
\fBMAX_MEMBERS_PER_GROUP\fR (number)
.RS 4
Maximum members per group entry\&. When the maximum is reached, a new group entry (line) is started in
/etc/group
(with the same name, same password, and same GID)\&.
.sp
The default value is 0, meaning that there are no limits in the number of members in a group\&.
.sp
This feature (split group) permits to limit the length of lines in the group file\&. This is useful to make sure that lines for NIS groups are not larger than 1024 characters\&.
.sp
If you need to enforce such limit, you can use 25\&.
.sp
Note: split groups may not be supported by all tools (even in the Shadow toolsuite)\&. You should not use this variable unless you really need it\&.
.RE
.PP
\fBPASS_MAX_DAYS\fR (number)
.RS 4
The maximum number of days a password may be used\&. If the password is older than this, a password change will be forced\&. If not specified, \-1 will be assumed (which disables the restriction)\&.
.RE
.PP
\fBPASS_MIN_DAYS\fR (number)
.RS 4
The minimum number of days allowed between password changes\&. Any password changes attempted sooner than this will be rejected\&. If not specified, \-1 will be assumed (which disables the restriction)\&.
.RE
.PP
\fBPASS_WARN_AGE\fR (number)
.RS 4
The number of days warning given before a password expires\&. A zero means warning is given only upon the day of expiration, a negative value means no warning is given\&. If not specified, no warning will be provided\&.
.RE
.PP
\fBSUB_GID_MIN\fR (number), \fBSUB_GID_MAX\fR (number), \fBSUB_GID_COUNT\fR (number)
.RS 4
If
/etc/subuid
exists, the commands
\fBuseradd\fR
and
\fBnewusers\fR
(unless the user already have subordinate group IDs) allocate
\fBSUB_GID_COUNT\fR
unused group IDs from the range
\fBSUB_GID_MIN\fR
to
\fBSUB_GID_MAX\fR
for each new user\&.
.sp
The default values for
\fBSUB_GID_MIN\fR,
\fBSUB_GID_MAX\fR,
\fBSUB_GID_COUNT\fR
are respectively 100000, 600100000 and 65536\&.
.RE
.PP
\fBSUB_UID_MIN\fR (number), \fBSUB_UID_MAX\fR (number), \fBSUB_UID_COUNT\fR (number)
.RS 4
If
/etc/subuid
exists, the commands
\fBuseradd\fR
and
\fBnewusers\fR
(unless the user already have subordinate user IDs) allocate
\fBSUB_UID_COUNT\fR
unused user IDs from the range
\fBSUB_UID_MIN\fR
to
\fBSUB_UID_MAX\fR
for each new user\&.
.sp
The default values for
\fBSUB_UID_MIN\fR,
\fBSUB_UID_MAX\fR,
\fBSUB_UID_COUNT\fR
are respectively 100000, 600100000 and 65536\&.
.RE
.PP
\fBSYS_GID_MAX\fR (number), \fBSYS_GID_MIN\fR (number)
.RS 4
Range of group IDs used for the creation of system groups by
\fBuseradd\fR,
\fBgroupadd\fR, or
\fBnewusers\fR\&.
.sp
The default value for
\fBSYS_GID_MIN\fR
(resp\&.
\fBSYS_GID_MAX\fR) is 101 (resp\&.
\fBGID_MIN\fR\-1)\&.
.RE
.PP
\fBSYS_UID_MAX\fR (number), \fBSYS_UID_MIN\fR (number)
.RS 4
Range of user IDs used for the creation of system users by
\fBuseradd\fR
or
\fBnewusers\fR\&.
.sp
The default value for
\fBSYS_UID_MIN\fR
(resp\&.
\fBSYS_UID_MAX\fR) is 101 (resp\&.
\fBUID_MIN\fR\-1)\&.
.RE
.PP
\fBUID_MAX\fR (number), \fBUID_MIN\fR (number)
.RS 4
Range of user IDs used for the creation of regular users by
\fBuseradd\fR
or
\fBnewusers\fR\&.
.sp
The default value for
\fBUID_MIN\fR
(resp\&.
\fBUID_MAX\fR) is 1000 (resp\&. 60000)\&.
.RE
.PP
\fBUMASK\fR (number)
.RS 4
The file mode creation mask is initialized to this value\&. If not specified, the mask will be initialized to 022\&.
.sp
\fBuseradd\fR
and
\fBnewusers\fR
use this mask to set the mode of the home directory they create
.sp
It is also used by
\fBlogin\fR
to define users\*(Aq initial umask\&. Note that this mask can be overridden by the user\*(Aqs GECOS line (if
\fBQUOTAS_ENAB\fR
is set) or by the specification of a limit with the
\fIK\fR
identifier in
\fBlimits\fR(5)\&.
.RE
.PP
\fBUSERGROUPS_ENAB\fR (boolean)
.RS 4
Enable setting of the umask group bits to be the same as owner bits (examples: 022 \-> 002, 077 \-> 007) for non\-root users, if the uid is the same as gid, and username is the same as the primary group name\&.
.sp
If set to
\fIyes\fR,
\fBuserdel\fR
will remove the user\*(Aqs group if it contains no more members, and
\fBuseradd\fR
will create by default a group with the name of the user\&.
.RE
.SH "FILES"
.PP
/etc/passwd
.RS 4
User account information\&.
.RE
.PP
/etc/shadow
.RS 4
Secure user account information\&.
.RE
.PP
/etc/group
.RS 4
Group account information\&.
.RE
.PP
/etc/gshadow
.RS 4
Secure group account information\&.
.RE
.PP
/etc/default/useradd
.RS 4
Default values for account creation\&.
.RE
.PP
/etc/skel/
.RS 4
Directory containing default files\&.
.RE
.PP
/etc/subgid
.RS 4
Per user subordinate group IDs\&.
.RE
.PP
/etc/subuid
.RS 4
Per user subordinate user IDs\&.
.RE
.PP
/etc/login\&.defs
.RS 4
Shadow password suite configuration\&.
.RE
.SH "EXIT VALUES"
.PP
The
\fBuseradd\fR
command exits with the following values:
.PP
\fI0\fR
.RS 4
success
.RE
.PP
\fI1\fR
.RS 4
can\*(Aqt update password file
.RE
.PP
\fI2\fR
.RS 4
invalid command syntax
.RE
.PP
\fI3\fR
.RS 4
invalid argument to option
.RE
.PP
\fI4\fR
.RS 4
UID already in use (and no
\fB\-o\fR)
.RE
.PP
\fI6\fR
.RS 4
specified group doesn\*(Aqt exist
.RE
.PP
\fI9\fR
.RS 4
username already in use
.RE
.PP
\fI10\fR
.RS 4
can\*(Aqt update group file
.RE
.PP
\fI12\fR
.RS 4
can\*(Aqt create home directory
.RE
.PP
\fI14\fR
.RS 4
can\*(Aqt update SELinux user mapping
.RE
.SH "SEE ALSO"
.PP
\fBchfn\fR(1),
\fBchsh\fR(1),
\fBpasswd\fR(1),
\fBcrypt\fR(3),
\fBgroupadd\fR(8),
\fBgroupdel\fR(8),
\fBgroupmod\fR(8),
\fBlogin.defs\fR(5),
\fBnewusers\fR(8),
\fBsubgid\fR(5), \fBsubuid\fR(5),
\fBuserdel\fR(8),
\fBusermod\fR(8)\&.