useradd（将用户添加到系统）_语法_示例_Unix&Linux命令

在类似Unix的操作系统上，useradd命令创建一个新用户或为新用户设置默认信息。本文档介绍了useradd的Linux版本。

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Linux

useradd是用于将用户添加到系统的低级实用程序。通常，应该使用更友好的adduser。

您的操作系统可能附带稍微不同的useradd版本。在使用它创建新帐户之前，请先检查您的文档。本文档引用了一些经常在基于Debian的Linux变体上使用的选项，但它们代表了useradd的一般用法。

如果在不使用-D选项的情况下调用useradd命令，则会使用命令行上指定的值以及系统的默认值来创建新的用户帐户。根据命令行选项，useradd命令将更新系统文件，并且还可以创建新用户的主目录并复制初始文件。

默认情况下，还将为新用户创建一个组（请参见下面的-g，-N，-U选项和USERGROUPS_ENAB变量）。

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useradd [options] LOGIN

useradd -D

useradd -D [options]

选项

-c，-- comment COMMENT	COMMENT可以是任何文本字符串。它通常是login的简短描述，当前用作用户全名的字段。
-d，--home HOME_DIR	将使用HOME_DIR作为用户登录目录的值来创建新用户。默认是将LOGIN名称附加到BASE_DIR并将其用作登录目录名称。目录HOME_DIR不必存在，但是如果缺少，则不会创建。
-D，--defaults	设置新的默认值。请参阅下面有关更改新用户默认值的部分。
-e，-- expiredate EXPIRE_DATE	用户帐户将被禁用的日期。日期以YYYY-MM-DD格式指定。如果未指定，则useradd将使用/ etc / default / useradd中EXPIRE变量指定的默认到期日期，或者默认为空字符串（无到期）。
-f，-- inactive INACTIVE	密码过期后直到永久禁用该帐户的天数。密码过期后，值0将禁用该帐户，而值-1将禁用该功能。如果未指定，则useradd将使用/ etc / default / useradd中的INACTIVE变量指定的默认非活动期，或者默认为-1。
-g，-- gid GROUP	用户初始登录组的组名或编号。组名必须存在。组号必须引用已经存在的组。如果未指定，则useradd的行为将取决于/etc/login.defs中的USERGROUPS_ENAB变量。如果将此变量设置为yes（或在命令行上指定-U / --user-group），则将为该用户创建一个与登录名相同的组。如果变量设置为no（或在命令行上指定-N / --no-user-group），则useradd会将新用户的主要组设置为GROUP所指定的值/ etc / default / useradd中的变量，或者默认为100。
-G，-- groups GROUP1 [，GROUP2，... [，GROUPN ]]]	包含用户作为成员的组的列表。每一组之间用逗号隔开，中间没有空格。这些组与-g选项给定的组受到相同的限制。默认设置是用户仅属于初始组。
-h，--help	显示帮助消息，然后退出。
-k，-- skel SKEL_DIR	SKEL_DIR是框架目录，当用户目录由useradd创建时，它包含要复制到用户主目录中的文件和目录。仅当指定了-m（或--create-home）选项时，此选项才有效。如果未设置此选项，则框架目录由/ etc / default / useradd中的SKEL变量或默认情况下/ etc / skel中的SKEL变量定义。如果可能，将复制ACL和扩展属性。
-K，-- key KEY = VALUE	覆盖/etc/login.defs的默认值（UID_MIN，UID_MAX，UMASK，PASS_MAX_DAYS等）。示例：-K PASS_MAX_DAYS = -1可以在创建系统帐户以关闭密码时限时使用，即使系统帐户根本没有密码也是如此。可以指定多个-K选项，例如：-K UID_MIN = 100 -K UID_MAX = 499
-l，--no-log-init	不要将用户添加到lastlog和faillog数据库。默认情况下，将重置lastlog和faillog数据库中的用户条目，以避免重用先前删除的用户的条目。为了与以前版本的兼容性useradd的，在-O选项也支持这一目的。
-m，-- create-home	如果用户的主目录不存在，则创建它。骨架目录（可以使用-k选项定义）中包含的文件和目录将被复制到主目录。默认情况下，如果未指定此选项并且未启用CREATE_HOME，则不会创建主目录。
-M	难道没有创建用户的主目录，即使从广角设置系统/etc/login.defs的（CREATE_HOME）设置为是。
-N，-- no-user-group	不要创建与用户同名的组，而是将用户添加到-g选项或/ etc / default / useradd中的GROUP变量指定的组中。缺省行为（如果未指定-g，-N和-U选项）由/etc/login.defs中的USERGROUPS_ENAB变量定义。
-o，--non-unique	允许创建具有重复（非唯一）UID的用户帐户。该选项仅与-u选项结合使用才有效。
-p，-- password PASSWORD	该加密的密码，通过隐窝返回。默认为禁用密码。注意：不建议使用此选项，因为列出进程的用户（例如，使用ps命令）将看到密码（或加密密码）。您应该确保密码遵守系统的密码策略。
-r，--system	创建一个系统帐户。将在/ etc / shadow中创建不带任何老化信息的系统用户，并在/etc/login.defs中定义的SYS_UID_MIN-SYS_UID_MAX范围内选择其数字标识符，而不是UID_MIN-UID_MAX（及其创建时使用的GID副本）组）。请注意，useradd命令不会创建这样一个用户的主目录，而不管默认设置的/etc/login.defs的（CREATE_HOME）。如果要创建系统帐户的主目录，则必须指定-m选项。
-R，--root CHROOT_DIR	在应用更改CHROOT_DIR目录，并从使用配置文件CHROOT_DIR目录。
-s，-- shell SHELL	用户的登录shell的名称。缺省值是将该字段保留为空白，这使系统选择/ etc / default / useradd中的SHELL变量指定的缺省登录shell ，或者缺省情况下为空字符串。
-u，--uid UID	用户ID的数值。除非使用-o选项，否则该值必须唯一。该值必须为非负数。默认值为使用大于或等于UID_MIN且大于其他所有用户的最小ID值。另请参见-r选项和UID_MAX描述。
-U，-- user-group	创建一个与用户同名的组，然后将该用户添加到该组中。缺省行为（如果未指定-g，-N和-U选项）由/etc/login.defs中的USERGROUPS_ENAB变量定义。
-Z，-- selinux-user SEUSER	SELinux用户，用于用户登录。默认值是将该字段保留为空白，这将导致系统选择默认的SELinux用户。

更改新用户默认值

仅使用-D选项调用时，useradd将显示当前默认值。与-D和其他选项一起调用时，useradd将更新指定选项的默认值。

有效的默认更改选项为：

-b，-- base-dir BASE_DIR	新用户主目录的路径前缀。如果在创建新帐户时未使用-d选项，则将用户名附加到BASE_DIR的末尾以形成新用户的主目录名。此选项在/ etc / default / useradd中设置HOME变量。
-e，-- expiredate EXPIRE_DATE	禁用用户帐户的日期。此选项在/ etc / default / useradd中设置EXPIRE变量。
-f，-- inactive INACTIVE	密码过期后的天数，帐户将被禁用。此选项在/ etc / default / useradd中设置INACTIVE变量。
-g，-- gid GROUP	新用户的初始组的组名或ID（使用-N / --no-user-group或/etc/login.defs中的USERGROUPS_ENAB变量设置为no时）。命名组必须存在，并且数字组ID必须具有现有条目。此选项在/ etc / default / useradd中设置GROUP变量。
-s，-- shell SHELL	新用户的登录外壳名称。此选项在/ etc / default / useradd中设置SHELL变量。

注意

系统管理员负责将默认用户文件放置在/ etc / skel /目录（或在/ etc / default / useradd或命令行中指定的任何其他框架目录）中。

注意事项

您不能将用户添加到NIS或LDAP组。这必须在相应的服务器上执行。

同样，如果用户名已经存在于NIS或LDAP等外部用户数据库中，则useradd将拒绝用户帐户创建请求。

通常建议仅使用以小写字母或下划线开头，后接小写字母，数字，下划线或破折号的用户名。它们可以以美元符号结尾。描述有效用户名的正则表达式为：

[a-z _] [a-z0-9 _-] * [$]？

唯一的限制是用户名既不能以破折号（' - '）或加号（' + '）或代字号（' 〜 '）开头，也不能包含冒号（' ： '），逗号（' ， '）或空格（空格：“”，行尾：“ \ n ”，制表符：“ \ t ”，等等）。请注意，使用斜杠（' / '）可能会破坏用于定义用户主目录的默认算法。

用户名最多只能包含32个字符。

组态

/etc/login.defs中的以下配置变量更改了此工具的行为：

名称	类型	描述
CREATE_HOME	布尔值	指示默认情况下是否应为新用户创建主目录。此设置不适用于系统用户，可以在命令行上覆盖。
GID_MAX，GID_MIN	数	useradd，groupadd或newusers用于创建常规组的组ID范围。作为默认值GID_MIN是1000 ; GID_MAX的默认值为60000。
MAIL_DIR	串	邮件假脱机目录。当邮箱的相应用户帐户被修改或删除时，需要用它来操作邮箱。如果未指定，则使用编译时默认值。
MAIL_FILE	串	定义用户邮件假脱机文件相对于其主目录的位置。

该MAIL_DIR和MAIL_FILE变量由useradd的，usermod命令，和则userdel创建，移动或删除用户的邮件池。

MAX_MEMBERS_PER_GROUP	数	每个组条目的最大成员数。当达到最大值时，将在/ etc / group中启动一个新的组条目（行）（具有相同的名称，相同的密码和相同的组ID）。默认值为0，表示组中的成员数没有限制。此功能（拆分组）可以帮助限制组文件中的行长。确保NIS组的行不超过1024个字符非常有用。如果您需要强制执行此限制，则可以使用25。注意：并非所有工具都支持拆分组，即使阴影工具套件等高级工具也不支持。除非确实需要，否则不应使用此变量。
PASS_MAX_DAYS	数	密码可以使用的最大天数。如果密码早于此密码，则将强制更改密码。如果未指定，则将假定为-1（禁用限制）。
PASS_MIN_DAYS	数	两次密码更改之间允许的最少天数。早于此时间进行的任何密码更改都将被拒绝。如果未指定，则将假定为-1（禁用限制）。
PASS_WARN_AGE	数	密码过期前给出的警告天数。零表示仅在到期日发出警告，负值表示不发出警告。如果未指定，则不会提供警告。
SYS_GID_MAX，SYS_GID_MIN	数	useradd，groupadd或newusers用于创建系统组的组ID范围。作为默认值SYS_GID_MIN是101 ; 默认值SYS_GID_MAX是GID_MIN减1。
SYS_UID_MAX，SYS_UID_MIN	数	useradd或newusers用于创建系统用户的用户ID范围。作为默认值SYS_UID_MIN是101 ; 默认值SYS_UID_MAX是UID_MIN减1。
UID_MAX，UID_MIN	数	useradd或newusers用于创建常规用户的用户ID范围。UID_MIN（分别为UID_MAX）的默认值为1000（分别为60000）。
UMASK	数	该文件模式创建掩码被初始化为这个值。如果未指定，则掩码将初始化为022。useradd和newusers使用此掩码设置他们创建的主目录的模式。pam_umask也将其用作默认的umask值。
USERGROUPS_ENAB	布尔值	如果设置为yes，则userdel将删除该用户的组（如果该组中不再包含任何成员），并且useradd将默认创建一个具有用户名的组。

档案

/ etc / passwd	用户帐户信息。
/ etc / shadow	安全的用户帐户信息。
/ etc / group	组帐户信息。
/ etc / gshadow	安全的组帐户信息。
/ etc / default / useradd	创建帐户的默认值。
/ etc / skel /	包含默认文件的目录。
/etc/login.defs	影子密码套件配置。

退出状态

useradd退出时具有以下状态，具体取决于发生的情况：

0	一切均已成功完成。
1	无法更新密码文件。
2	该命令的语法无效。
3	给一个或多个选项一个无效的参数。
4	用户标识已在使用中，并且未指定-o。
6	指定的组不存在。
9	用户名已被使用。
10	无法更新群组档案。
12	无法创建主目录。
14	无法更新SE Linux用户映射。

useradd [options] LOGIN

useradd -D

useradd -D [options]

Options

-c, --comment COMMENT	COMMENT can be any text string. It is generally a short description of the login, and is currently used as the field for the user's full name.
-d, --home HOME_DIR	The new user will be created using HOME_DIR as the value for the user's login directory. The default is to append the LOGIN name to BASE_DIR and use that as the login directory name. The directory HOME_DIR does not have to exist but will not be created if it is missing.
-D, --defaults	Set new default values. See the section on Changing New User Default Values, below.
-e, --expiredate EXPIRE_DATE	The date on which the user account will be disabled. The date is specified in the format YYYY-MM-DD. If not specified, useradd will use the default expiry date specified by the EXPIRE variable in /etc/default/useradd, or an empty string (no expiry) by default.
-f, --inactive INACTIVE	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. If not specified, useradd will use the default inactivity period specified by the INACTIVE variable in /etc/default/useradd, or -1 by default.
-g, --gid GROUP	The group name or number of the user's initial login group. The group name must exist. A group number must refer to an already existing group. If not specified, the behavior of useradd will depend on the USERGROUPS_ENAB variable in /etc/login.defs. If this variable is set to yes (or -U/--user-group 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 no (or -N/--no-user-group is specified on the command line), useradd will set the primary group of the new user to the value specified by the GROUP variable in /etc/default/useradd, or 100 by default.
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]	A list of groups containing the user as a member. 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 -g option. The default is for the user to belong only to the initial group.
-h, --help	Display a help message, and exit.
-k, --skel SKEL_DIR	SKEL_DIR is the skeleton directory, which contains files and directories to be copied in the user's home directory, when the home directory is created by useradd. This option is only valid if the -m (or --create-home) option is specified. If this option is not set, the skeleton directory is defined by the SKEL variable in /etc/default/useradd or, by default, /etc/skel. If possible, the ACL and extended attributes are copied.
-K, --key KEY=VALUE	Overrides /etc/login.defs defaults (UID_MIN, UID_MAX, UMASK, PASS_MAX_DAYS and others). Example: -K PASS_MAX_DAYS=-1 can be used when creating system account to turn off password aging, even though system account has no password at all. Multiple -K options can be specified, for example: -K UID_MIN=100 -K UID_MAX=499
-l, --no-log-init	Do not add the user to the lastlog and faillog databases. By default, the user's entries in the lastlog and faillog databases are resetted to avoid reusing the entry from a previously deleted user. For the compatibility with previous versions of useradd, the -O option is also supported for this purpose.
-m, --create-home	Create the user's home directory if it does not exist. The files and directories contained in the skeleton directory (which can be defined with the -k option) will be copied to the home directory. By default, if this option is not specified and CREATE_HOME is not enabled, no home directories are created.
-M	Do no create the user's home directory, even if the system wide setting from /etc/login.defs (CREATE_HOME) is set to yes.
-N, --no-user-group	Do not create a group with the same name as the user, but add the user to the group specified by the -g option or by the GROUP variable in /etc/default/useradd. The default behavior (if the -g, -N, and -U options are not specified) is defined by the USERGROUPS_ENAB variable in /etc/login.defs.
-o, --non-unique	Allow the creation of a user account with a duplicate (non-unique) UID. This option is only valid in combination with the -u option.
-p, --password PASSWORD	The encrypted password, as returned by crypt. The default is to disable the password. Note: This option is not recommended because the password (or encrypted password) will be visible by users listing the processes (for example, with the ps command). You should make sure the password respects the system's password policy.
-r, --system	Create a system account. System users will be created with no aging information in /etc/shadow, and their numeric identifiers are chosen in the SYS_UID_MIN-SYS_UID_MAX range, defined in /etc/login.defs, instead of UID_MIN-UID_MAX (and their GID counterparts for the creation of groups). Note that useradd will not create a home directory for such an user, regardless of the default setting in /etc/login.defs (CREATE_HOME). You have to specify the -m options if you want a home directory for a system account to be created.
-R, --root CHROOT_DIR	Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.
-s, --shell SHELL	The name of the user's login shell. The default is to leave this field blank, which causes the system to select the default login shell specified by the SHELL variable in /etc/default/useradd, or an empty string by default.
-u, --uid UID	The numerical value of the user's ID. This value must be unique, unless the -o option is used. The value must be non-negative. The default is to use the smallest ID value greater than or equal to UID_MIN and greater than every other user. See also the -r option and the UID_MAX description.
-U, --user-group	Create a group with the same name as the user, and add the user to this group. The default behavior (if the -g, -N, and -U options are not specified) is defined by the USERGROUPS_ENAB variable in /etc/login.defs.
-Z, --selinux-user SEUSER	The SELinux user for the user's login. The default is to leave this field blank, which causes the system to select the default SELinux user.

Changing New User Default Values

When invoked with only the -D option, useradd displays the current default values. When invoked with -D plus other options, useradd will update the default values for the specified options.

Valid default-changing options are:

-b, --base-dir BASE_DIR	The path prefix for a new user's home directory. The user's name will be affixed to the end of BASE_DIR to form the new user's home directory name, if the -d option is not used when creating a new account. This option sets the HOME variable in /etc/default/useradd.
-e, --expiredate EXPIRE_DATE	The date on which the user account is disabled. This option sets the EXPIRE variable in /etc/default/useradd.
-f, --inactive INACTIVE	The number of days after a password has expired before the account will be disabled. This option sets the INACTIVE variable in /etc/default/useradd.
-g, --gid GROUP	The group name or ID for a new user's initial group (when the -N/--no-user-group is used or when the USERGROUPS_ENAB variable is set to no in /etc/login.defs). The named group must exist, and a numerical group ID must have an existing entry. This option sets the GROUP variable in /etc/default/useradd.
-s, --shell SHELL	The name of a new user's login shell. This option sets the SHELL variable in /etc/default/useradd.

Notes

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).

Caveats

You may not add a user to a NIS or LDAP group. This must be performed on the corresponding server.

Similarly, if the username already exists in an external user database such as NIS or LDAP, useradd will deny the user account creation request.

It is usually recommended to only use usernames that begin with a lower case letter or an underscore, followed by lower case letters, digits, underscores, or dashes. They can end with a dollar sign. The regular expression which describes a valid username is:

[a-z_][a-z0-9_-]*[$]?

The only constraints are that usernames must neither start with a dash ('-') nor plus ('+') nor tilde ('~') nor contain a colon (':'), a comma (','), or a whitespace (space: ' ', end of line: '\n', tab: '\t', etc.). Note that using a slash ('/') may break the default algorithm for the definition of the user's home directory.

Usernames may only be up to 32 characters long.

Configuration

The following configuration variables in /etc/login.defs change the behavior of this tool:

name	type	description
CREATE_HOME	boolean	Indicate if a home directory should be created by default for new users. This setting does not apply to system users, and can be overridden on the command line.
GID_MAX, GID_MIN	number	Range of group IDs used for the creation of regular groups by useradd, groupadd, or newusers. The default value for GID_MIN is 1000; the default for GID_MAX is 60000.
MAIL_DIR	string	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.
MAIL_FILE	string	Defines the location of the users mail spool files relatively to their home directory.

The MAIL_DIR and MAIL_FILE variables are used by useradd, usermod, and userdel to create, move, or delete the user's mail spool.

MAX_MEMBERS_PER_GROUP	number	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 group ID). The default value is 0, meaning that there are no limits in the number of members in a group. This feature (split group) can help 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. If you need to enforce such limit, you can use 25. Note: split groups may not be supported by all tools, even advanced tools like the Shadow toolsuite. You should not use this variable unless you really need it.
PASS_MAX_DAYS	number	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).
PASS_MIN_DAYS	number	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).
PASS_WARN_AGE	number	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.
SYS_GID_MAX, SYS_GID_MIN	number	Range of group IDs used for the creation of system groups by useradd, groupadd, or newusers. The default value for SYS_GID_MIN is 101; the default value for SYS_GID_MAX is GID_MIN minus 1.
SYS_UID_MAX, SYS_UID_MIN	number	Range of user IDs used for the creation of system users by useradd or newusers. The default value for SYS_UID_MIN is 101; the default value of SYS_UID_MAX is UID_MIN minus 1.
UID_MAX, UID_MIN	number	Range of user IDs used for the creation of regular users by useradd or newusers. The default value for UID_MIN (resp. UID_MAX) is 1000 (resp. 60000).
UMASK	number	The file mode creation mask is initialized to this value. If not specified, the mask will be initialized to 022. useradd and newusers use this mask to set the mode of the home directory they create. It is also used by pam_umask as the default umask value.
USERGROUPS_ENAB	boolean	If set to yes, userdel will remove the user's group if it contains no more members, and useradd will create by default a group with the name of the user.

Files

/etc/passwd	User account information.
/etc/shadow	Secure user account information.
/etc/group	Group account information.
/etc/gshadow	Secure group account information.
/etc/default/useradd	Default values for account creation.
/etc/skel/	Directory containing default files.
/etc/login.defs	Shadow password suite configuration.

Exit Status

useradd exits with the following status, depending on what occurred:

0	Everything was completed successfully.
1	Couldn't update the password file.
2	The syntax of the command was invalid.
3	One or more options were given an invalid argument.
4	User ID is already in use, and -o was not specified.
6	Specified group doesn't exist.
9	Username already in use.
10	Couldn't update the group file.
12	Couldn't create the home directory.
14	Couldn't update SE Linux user mapping.

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useradd -D

显示新用户的默认值。输出类似于以下内容：

GROUP=1001
HOME=/home
INACTIVE=-1
EXPIRE=
SHELL=/bin/bash
SKEL=/etc/skel
CREATE_MAIL_SPOOL=no

useradd newperson

创建newperson新用户。添加新用户后，您将需要使用passwd命令为该帐户分配密码。

创建用户后，您可以使用usermod命令修改任何用户设置，例如用户的主目录。

useradd -D

Displays the defaults for new users. Output resembles the following:

GROUP=1001
HOME=/home
INACTIVE=-1
EXPIRE=
SHELL=/bin/bash
SKEL=/etc/skel
CREATE_MAIL_SPOOL=no

useradd newperson

Creates newperson as a new user. Once the new user has been added, you would need to use the passwd command to assign a password to the account.

Once a user has been created, you can modify any of the user settings, such as the user's home directory, using the usermod command.

为了使这些命令起作用，您必须具有root特权。

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useradd

useradd 运行系统环境

useradd 描述

useradd 语法

useradd 示例