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This article mainly explains the "commands to add users and user groups under Linux". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "commands to add users and user groups under Linux".

Useradd

Useradd [- c comment] [- d home_dir]

[- e expire_date] [- f inactive_time]

[- g initial_group] [- G group [,...]]

[- m [- k skeleton_dir] |-M] [- s shell]

[- u uid [- o]] [- n] [- r] login

Useradd-D [- g default_group] [- b default_home]

[- f default_inactive] [- e default_expire_date]

[- s default_shell]

Set up a new account

When the-D parameter is not added, the useradd instruction uses the command line to specify the set value of the new account and usage system

The default value on the. The new user account will generate some system files, user directory creation and copy.

Prepare starting files, etc., which can be specified using command line options. This version is mentioned by Red Hat Linux

For each new user to create a separate group, there is no need to add the-n option. Useradd

The options available are

-c comment

The description field of the new account password file.

-d home_dir

The home_dir used each time the new account logs in. The default value is the login name in default_home

And as the directory name when logging in

-e expire_date

Account termination date. The specified format of the date is MM/DD/YY.

-f inactive_days

The account will be permanently suspended a few days after the account expires. When the value is 0, the account is suspended immediately. And the duty is

This feature is disabled at-1, with a default value of-1

-g initial_group

Group name or number as the user login starting group (group). The group name must be

The name of an existing existence. The group number must also be an existing group. Preset number of groups

The word is 1.

-G group, [...]

Define this consumer as a member of this pile of groups. Each group uses the "," area.

Cannot be mixed with white space characters.

The group name is the same as the-g option. Defines the value as the starting group of the user.

The-m user directory is automatically created if it does not exist. If you use the file in the-k option skeleton_dir

Will be copied to the user directory. However, the files in the / etc/skel directory will also be copied.

Replace. Any directory in skeleton_dir or/etc/skel will be the same in the user directory

As soon as it is established. The-k does not establish a directory with-m and does not copy any files as default values.

-M does not create a user directory, even if the / etc/login.defs system file is set to create a user directory

.

-n the default user group and user name will be the same. This option cancels this default value.

-r this parameter is used to establish a system account. The UID of the system account will be more than defined on the system file

/ etc/login.defs. The UID_MIN is small. Note that the account created by this usage of useradd is not

Will create a user directory, and will not care about the record in / etc/login.defs. The defined value of the If

If you want to have a user directory, you have to specify the-m parameter to create a system account. This is RED HAT.

Additional options.

-s shell

The shell name used by the user after logging in. The default is not to fill in, so the system will help you point to

Set the default login shell.

-u the ID value of the uid user. Must be a unique ID value unless you use the-o option. The number cannot be negative.

Value. The default is that the minimum must not be less than 999 and increase one by one. 0999 is traditionally reserved for the system

Account number is used.

Change the preset value

When the-D option appears, useradd shows the current default value, or updates it from the command line

Default value. The available options are ∶

-b default_home

Defines the previous directory of the directory to which the user belongs. The user name is appended to the default_home

The directory that is later used to create the new user. Of course, this option has no effect after using-d.

-e default_expire_date

The end date of the user account.

-f default_inactive

The account will be suspended after a few days of expiration.

-g default_group

The new account starts with the group name or ID. The group name must be an existing name. Group I D is also required

Is an existing group.

-s default_shell

The shell name used by the user after logging in. All new accounts will use this shell.

If no parameters are specified, useradd displays the currently preset values.

Notes

System administrators have an obligation to place user-defined files in the / etc/skel directory.

This version of "useradd" is modified by Red Hat.

Warning

No new users can be added to the NIS group. You must run it on the NIS server.

archives

/ etc/passwd- user account information

/ etc/shadow- user account information encryption

/ etc/group- group information

/ etc/default/useradd- definition Information

/ etc/login.defs- system generalized setting

/ etc/skel- the directory containing the definition file

Example:

The code is as follows:

[root@Blackghost ~] useradd tank # add user

[root@Blackghost ~] useradd-r zhangy # add system user

[root@Blackghost ~] useradd-d / home/zhangying zhangying # add a user and specify the home directory

[root@Blackghost ~] useradd-g mytest-d / home/hao hao # add users, specify groups, and set the home directory

[root@Blackghost ~] useradd-e 04swap 05max 13 fxxk # add users and set validity period for users

Groupadd

Groupadd- sets up a new group

Groupadd [- ggid [- o]] [- r] [- f] group [[]]

Groupadd can specify a group name to create a new group account. New group values can be obtained from the system as needed. The following options are available for groupadd.

-g gid ID value. The value must be unique and not the same unless the-o parameter is used. The value cannot be negative. The default is that the minimum must not be less than 500 and increase one by one. 0room499 is traditionally reserved for system accounts.

-r this parameter is used to establish a system account. It will automatically help you select a gid less than 499 unless you add the-g argument to the command line. This is an additional option for RED HAT.

-f this is the force logo. When you add an existing group account, the system will get an error message and end the groupadd. If this is the case, the group will not be changed (or added again) and the-g option can be added at the same time. When you add a gid, gid does not have to be the only value, but without the-o parameter, the result will be displayed after the group is built. This is an additional option for RED HAT.

archives

/ etc/group-group account information

/ etc/gshadow-secure group account information

Example:

Add a user group

The code is as follows:

[root@Blackghost ~] groupadd mytest

Add a user group and specify GID

The code is as follows:

[root@Blackghost] groupadd-g 444 test

Thank you for reading, the above is the content of "add users and user groups commands under Linux". After the study of this article, I believe you have a deeper understanding of the problem of adding users and user groups commands under Linux, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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