Linux Systems-User management-Concepts and principlesA related concept
1/etc/passwd file Format: User name: Password bit: User identification number: Group identification number: Comment and other related description: Host directory: Default shell, column such as chengzhi:x:500:500:chengzhi-centos:/home/ Chengzhi:/bin/shell
2/etc/shadow file Format: User name: MD5 encrypted password (MD5 is one-way irreversible algorithm, fixed length): Last Modified time: Maximum time interval: Minimum time interval: warning Time: Idle time: Invalid file: Flag, previous two items are more important, the following understanding can be
3/etc/group file Format: User group: Group password (typically not used): Group ID (GID): List of users
4 Types of Linux users:superuser: Root user (uid=0)Pseudo-User: (uid=1~499) users associated with system processes and services, such as BIN,FTP, do not have a host directory, and typically do not log on to the systemNormal User: (uid=500~60000)
5 user groups:A user can contain multiple groupsEach group can contain multiple usersusers within a group have the same permissions
6/etc/passwd files and/etc/shadow files are user password files of Linux system, it is necessary to understand them, you can edit them to add ordinary users
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Linux Systems-User management-Concepts and principles
