<> Management of users and groups
<> user ：
/etc/passwd User managed profiles
System users ： Used to manage and run services , Login is not allowed by default /sbin/nologin
Ordinary users ： Self created users .
1. Add user
command ：useradd（ If you do not specify a group , Will be assigned a UID Private group of ）
2. Modify user information
3. Modify user home directory
method 1：
Create home directory while creating user
method 2：
If the user is not created at the same time as the user is created , At this time, switching users will fail
The following operations are required ：
4. delete user
userdel -r qwe -r Delete the home directory and mailbox assigned by the user
<> group ：
/etc/group
Classification of groups
Private group ： When creating a user , If no base group is specified for this user , Then the user will automatically assign the same user uid Private group of .
Basic group ：
Additional group ： Except for the basic group , Users can also be assigned to other groups .
Create group
Landing group
Modification group
delete group
groupdel
Add user group
gpasswd zuming Set password for group
gpasswd -a maomao zu1（ Group name ） Add group to user
gpasswd -M xixi,haha,maomao zu2 To add multiple users to a group in the form of a specified list
usermod -G zu1 maomao to maomao Users add additional groups
vim /etc/group Modify configuration file , Add the user name to the group's configuration file .
gpasswd -A maomao Designated team leader
gpasswd -d haha zu1 take haha User from zu1 Remove from
vim /etc/group Modify configuration file , Add the user name to the group's configuration file .
gpasswd -A maomao Designated team leader
gpasswd -d haha zu1 take haha User from zu1 Remove from
gpasswd -R zu1 Lock specified group , Only group members can enter this group
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