How to add a new system user in Linux

A simple user in Linux is not a simple useradd command. In fact, if you carefully check the Man document of useradd, you will find that [Syntax] adduser [required parameters] [Select

A simple Linux user is not a simple useradd command. In fact, if you carefully check the Man document of useradd, you will find more.

[Syntax] adduser [required parameters] [selective parameters] user name

[Function description] the adduser command adds users to the system based on the command line parameters. its configuration information is stored in/etc/adduser. in the conf file, if the "-- system" or "-- group" parameter is not specified during the call, the adduser command will add a general user by default, to add a system user, use the "-- symtem" parameter. to add a user group, use the "-- group" parameter.

[Parameter description]

The required parameters are described as follows:

Parameter functions

-R | -- system creates a system user

-- No-creat-home does not create the user's/home directory, even if it does not exist

-Q | -- quiet only displays warning information and error information, not general information

-- Debug for debugging

The optional parameters are described as follows:

Parameter functions

-D | -- home <目录> Specify the directory as the user's home directory

-S | -- shell |-s uses the specified SHELL as the user's shell for logon.

-U | -- uid <用户id> Use the specified user ID as the user ID instead of the default user ID.

-- Firstuid <用户id> The specified first user ID does not need to be crossed.

-- Lastid <用户id> You do not need to cross the specified last user ID

-Group <用户组> When a user is created, the user is assigned to the specified user group.

-- Disabled-password: The password is not set. you can log on

-- Disable-login does not set a password, but the user cannot log on until the password has been set

-- Ingroup <用户组> Add a user to a specified user group instead of creating a user group.

-- Add_extra_groups: adds the user to the additional user group specified by addr. conf.

-- Help |-h help information

-- Version

-- Conf <文件> Replace/etc/. adduser. conf with the specified file

-P | -- password <密码> Unadded user-specified encrypted password

[Parameter usage instructions]

-R | -- system: indicates "-r" or "-- system ".

-- Home <目录> : Add a directory after the "-- home" parameter, not <目录> The two words with angle brackets are actually directory paths.

[Execution example]

[Example 1] add a common user.

Root @ localhost :~ # Useradd kk // add user kk

[Example 2] specify a user group for the added user.

Root @ localhost :~ # Useradd-g root kk // add user kk and specify the user group as the root user group

[Example 3] create a system user.

Root @ localhost :~ # Useradd-r kk // create a system user kk

Example 4: specify the home directory for the newly added user.

Root @ localhost :~ # Useradd-d/home/myf kk // add user kk, whose home directory is/home/myf

When you log on to the host with the user name kk, the default system directory is/home/myf.

[Related commands]

Deluser, groupadd, usermod