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useradd/userdel Create a new user / Delete user , Need administrator permission to operate .
When creating users , If you don't configure the password , The user's default password is not available , therefore ,useradd Orders are generally related to passwd Use with commands , In the next section we will introduce this command .
useradd Options user name userdel Options user name
Classification of users
- The super user ：root, Have the highest administrative authority on the system ,UID The default is 0.
- Virtual user ： It is also called system user or pseudo user , With certain privileges , Related to system or program services , But there are no real users . Generally not used to log in to the system , It is mainly used to maintain the normal operation of an access , Such as ftp,apache etc. .
- Ordinary users ： It's a restricted user , Generally, new users are ordinary users . By default, only /bin、/usr/bin、/usr/local/bin And the commands in your home directory .
Be careful ：UID That is, the identity of each user , Although it can be modified /etc/passwd（ Command settings UID No repetition ）, But try to be unique , Similar to everyone's ID number. .
-c # Add remarks , Note text is saved in passwd In the remarks column . -d # Specify the home directory when the user logs in , Replace system defaults /home/< user name > -D # Change the default value . -e # Specify the expiration date of the account , The date format is MM/DD/YY, for example 06/30/12. The default means permanent . -f # Specify how many days after the password expires to close the account . If 0 The account was immediately deactivated ; If -1 Then the account is always available . The default value is -1. -g # Specify the group to which the user belongs . Value can make the group name GID. The user group must already exist , The default value of period is 100, namely users. -G # Specify the additional group to which the user belongs . -m # Automatically create user login directory . -M # Do not automatically create the user's login directory . -n # Cancel the creation of a group named by user name . -r # Set up a system account . -s # Specify the... Used by the user after login shell. The default value is /bin/bash. -u # Designated user ID Number . This value must be unique in the system .0~499 By default, it is reserved for the system user account , So the value must be greater than 499.
-f # Force deletion of user accounts -r # Delete the user's home directory and any files in it -h # Display help information for the command
useradd -s mingongge # New system user mingongge useradd mingongge -u 888 # Set up ID Try to be greater than 500, To avoid conflict ; commonly 0 To 499 The value between is left to bin、mail Such a system account useradd -m -d /home/mingongge mingongge # Specify the path to create the user's home directory ,/home/mingongge The directory will be created useradd -s /sbin/nologin mingongge # Create a user who doesn't have a home directory and can't log in useradd -m -G test,sudo mingongge # Add users to different user groups when creating test,sudo useradd -u 2020 -m -g root mingongge # Add users mingongge Its id by 2020, And add it to the group root in
Use useradd -D You can view the default information when creating a new user , Or directly cat /etc/default/useradd
useradd -D GROUP=888 HOME=/home INACTIVE=888 EXPIRE= SHELL=/bin/bash SKEL=/etc/skel CREATE_MAIL_SPOOL=yes
Modify the default information when creating a new user .
useradd -D -f 999 # Check whether the modification is successful useradd -D | grep INACTIVE INACTIVE=999
Delete user , But don't delete their home directories and files
[root@mingongge ~]# userdel mingongge
Delete user , And delete his home directory and files
[root@mingongge ~]# userdel -r mingongge
Force deletion of users
[root@mingongge ~]# userdel -f mingongge
In the next section we will introduce passwd This command , It is associated with useradd Commands are used in conjunction with , Used to configure / Change the user's password .