Linux User management command-useradd passwd usermod chage userdel su instance, useraddusermod

Linux User management command-useradd passwd usermod chage userdel su instance, useraddusermod

User's home directory

Common User:/home/user name. Both the owner and the group belong to this user. The permission is 700.

Super User:/root/the owner and group are both root users with the permission of 550

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Useradd [Option] User Name

Option:

-U UID: manually specify the user's UID

-D home directory

-C user description

-G group name: Specifies the initial group of the user.

-G group name: Specify the user's additional group

-S shell specifies the user's logon shell. The default value is/bin/shell.

Chage-d 0 user1 ===> in this way, you must change the password for user1 login.

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Passwd [Option] User Name

Option:

-S: query the password status of the user password, which is only used by the root user.

-L currently only root users are used

-U is used only by root to unlock the user.

-- Stdin can use the data output by the pipeline operator as the user's password

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Usermod

Usermod-c "indicates that the content is enclosed by spaces and enclosed in quotation marks." root => modify user description.

Usermod-G root user1 ==> add user1 user to the root group

Usermod-L user1 ==> lock user1

Usermod-U user ==> unlock user1

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Chage [Option] User Name

Option:

-L => exhausting the user's password status

-D ==> Date: last password change date (/etc/shadow)

-M ==> days: Password Change Interval (four fields)

-M ====> days: Password validity period (five fields)

-W ====> days: number of warning days before the password expires (six fields)

-I ====> days: Number of days after the password expires (seven characters)

-E ==> day account expiration time: (eight-character segment)

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Userdel

Userdel [-r] User Name

Option:

-R ==> delete a user's colleague to delete the user's home directory

Manually delete ==> the following content needs to be deleted

Vi/etc/passwd ==> Delete content containing user1

Vi/etc/shadow ==> Delete content containing user1

Vi/etc/group ==> Delete content containing user1

Vi/etc/gshadow ==> Delete content containing user1

Rm-rf/var/spool/mail/user1 ==> delete an email from user1.

Rm-rf/home/user1 ==> Delete the home Directory of user1

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Su ====> User Switching

Su [Option] User Name

-Use Only-indicates that the environment variables of associated users are switched together

-C only executes the command once without switching the command.

Example: su-root ==> switch to the root user

Su-root-c "useradd user1" ==> log on to www and use the root user to add a user1 user

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