Overview of user accounts in Linux7 inside
Super User: root: uid: = 0 gid = 0 maximum authority
Average user: uid> = 1000 general authority to do systems management, limited rights
Program users: 1 = <uid <1000 in order to enhance the security of the system, corresponding to the service in order to support the use of system resources, can not be used or landing system management system
User Account file
/ Etc / passwd: action to save the user name, host directory, login Shell and other basic information, each row corresponds to a user account records
Meaning a total of seven fields, each field representatives
root:x:0:0:root:/root:/bin/bash
The first field: user
The second field: password placeholder
The third field: uid
Fourth field: gid
The fifth field: User Notes
Sixth field: Host directory
Seventh field: login shell
Account password management
/etc/shadow
Save the user's password, account expiration date information, each row corresponds to an account password records
[root@douyanru ~]# head -1 /etc/shadow
root:$6$WqE0gdqm.U4asyeg$curSRozrZQCXqU0yxtNttcLn2f8KRl9D6uJfSsrLBlY75Qm7vZfuhkiaiOapf0nRXhI.Fx/Hk6oRw3CceqL9l0::0:99999:7:::
The first field: user account name
The second field: ciphertext
The third field: the account was last modified time from January 1, 1970 the number of days past
Fourth field: the number of days since the last change passwords can not change password
The fifth field: Distance password expiration days
Sixth field: mandatory password change time reminder
Seventh field: the number of days when the password expires that account is disabled
The eighth field: password expiration date