What is the linux add user command?

The command to add a user in Linux is "useradd". This command is the same as the adduser command. Its syntax is [useradd [-d home] [-s shell] [-c comment] [...] 】.

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The linux command to add a user is useradd

1. Function

The useradd or adduser command is used to establish a user account and create the user's starting directory. The usage permission is super user.

2. Format

useradd [-d home] [-s shell] [-c comment] [-m [-k template]] [-f inactive] [-e expire ] [-p passwd] [-r] name

3. Main parameters

　-c: Add remark text, remarks The text is saved in the remarks column of passwd.

　-d: Specify the home directory when the user logs in, replacing the system default value /home/

　-D: Change the default value.

-e: Specify the expiration date of the account. The date format is MM/DD/YY, such as 06/30/12. The default means it is permanently valid.

　-f: Specify the number of days after the password expires to close the account. If it is 0, the account will be deactivated immediately; if it is -1, the account will always be available. The default value is -1.

　-g: Specifies the group to which the user belongs. The value can be a group name or a GID. The user group must already exist, and the default value is 100, which is users.

　-G: Specify additional groups to which the user belongs.

　-m: Automatically create the user's login directory.

　-M: Do not automatically create the user's login directory.

　-n: Cancel the creation of a group named by the user name.

　-r: Create a system account.

　-s: Specify the shell used by the user after logging in. The default value is /bin/bash.

　-u: Specify the user ID number. This value must be unique in the system. 0~499 are reserved for system user accounts by default, so the value must be greater than 499.

4. Description

Useradd can be used to create a user account. It is the same as the adduser command. After the account is created, use passwd to set the password for the account. The account created using the useradd command is actually saved in the /etc/passwd text file.

5. Application Example

Create a new user account testuser1, and set the UID to 544. The home directory is /usr/testuser1 and belongs to the users group:

#useradd -u 544 -d /usr/testuser1  -g users -m  testuser1

Add -m If the home directory does not exist, it will be created automatically

6. Example

Use the administrator account to log in to the system and create user tmp_3452 with password 3sdt5:Eawhg

Add user command:

[root@ptr228 ~]# adduser tmp_3452

Change password command:

[root@ptr228 ~]# passwd tmp_3452

When the system prompts you to enter the password, enter the password: 3sdt5:Eawhg. The system prompts you to enter the confirmation password and then enter it again. . OK added successfully.

7.useradd adds users in batches

When using useradd, if you do not add any parameter options later, for example: #sudo useradd test The user created will be the default " Three "no" users: one has no Home Directory, two has no password, and three has no system shell.

The steps are as follows:

(1) Create the username list file username.txt (same as above)

(2) Create the user password corresponding file serc.txt in the format of username :password　(Pay attention to the format of the file)

stu1:tt1
stu2:tt2
stu3:tt3
stu4:tt4
stu5:tt5
stu6:tt6 　

(3) Batch added script file aa.sh

##添加用户，并且在/home/ 下为用户生成用户目录。cat < username.txt | xargs -n 1 useradd -m##批处理模式下更新密码
chpasswd < serc.txt##将上述的密码转换到密码文件和组文件
pwconv##结束验证信息
echo "OK 新建完成"(4)执行该脚本文件，查看执行过程
root@liu:/home/liu/Desktop/Dos# sh aa.sh

The useradd command is newly created and will not output anything if there is no error in execution. information and will not interact with the user. But users must remember those setting items, otherwise the added users may have some unexpected results.

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