14. Users and Groups in CentOS 7

Apr 16, 2024#CentOS7学习笔记203

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CentOS7 users and groups are managed through configuration files like /etc/passwd and /etc/group. Users have usernames, passwords, UID, GID, home directories, and shell programs. Groups can be private (created with users) or public (custom). Root user has maximum permissions, while regular users have limited permissions. Commands like useradd, passwd, userdel, groupadd, and groupdel are used to manage users and groups. Users can be added to groups using usermod or gpasswd commands.

Users and Groups in CentOS7#

root: Root User

Configuration Files for Users and Groups#

/etc/passwd: Users

Format:

Username:Password:UID:GID:User Directory:Shell Program

/etc/group: Groups

About Groups in Linux:#

Private Group: Created along with the user, named after the user
Public Group: Custom created

About Users in Linux:#

Root User: Highest authority as root
Regular User: Can use the Linux system, but with limited permissions

Add User: useradd

Set User Password: passwd

About User Directory: By default, when adding a user, a directory with the same name as the user will be created in /home

Delete User: userdel username -r (delete user directory simultaneously)

Add Group: groupadd

Delete Group: groupdel

For example: Add users tom and mike; password 123; create a public group student; add tom and mike to the student group

usermod -G groupname username		# Move user to group
or
gpasswd -a username groupname		# Add user to group
gpasswd -d username groupname		# Remove user from group