Linux from getting started to mastering-user management

I. User management commands

1. User's view

(1) View Current user

WHOAMI # #查看当前用户

(2) Viewing of users in the system

ID # #查看指定用户id信息

Id-u # #查看用户的uid

ID-G # #查看用户的gid

ID-G # #查看用户所在的所有组的id

Id-n # #显示名字而不显示id数字
2. User Switching

Su-User name # # # "-" identifies the current user's environment at the same time when user identity switching # # #

# # # Execution when the advanced user switch to low-level users do not need a password, low-level users switch to advanced needs, peer switching switching also need # # #

Note: Each time you switch to another user action opens a new shell process, you must exit with the Exit command and then switch to another user again.

3. How the user is stored in the system

/etc/passwd
User Information file
User name: Password: uid:gid: Description: Home directory: Default Shell

/etc/group
User group information file
Group name: Group password: Group ID: Group member

/etc/shadows
Certification Information file

/etc/skel/.*
By default the shell configuration is turned on, the user's bone file

/home/username
User's home directory

4. Deletion of the user

Userdel Student # #删除用户但是不删除用户的配置文件
Userdel-r Student # #删除用户并删除系统文件

5. User Establishment

******** User Information monitoring command **********

Watch-n 1 ' tail-n 3/etc/passwd/etc/group;ls-l/home ' # #加 "" means to monitor all subsequent commands. If there is no "" only monitor ";" before a command

                                                           ,         &NB Sp                          ,         &NB Sp                          ,         &NB Sp     # #在watch后面跟  -n 1  means one second monitoring                  

# #命令中的 ";" means the command before the semicolon is executed, followed by a semicolon.

(1)

Useradd # #建立用户的, when the user is established, read the/etc/login.defs file content determination rules
"After normal user id1000, super User ID before 200"

Useradd-u 8888 Student # #指定用户的uid

Useradd-g Student # #指定用户的初始组id, "The premise is that 21 user groups must be present"

Useradd-c ' haha ' student # #指定用户的说明

Useradd-g Student # #指定用户的附加组id, "The premise is that 21 user groups must be present"

useradd-d/HOME/WF Student # #指定用户的家目录

Useradd-s/bin/sh Student # #指定用户的默认shell

Userdel # #用户删除

"NOTE: Each time after the experiment to purify the user environment, that is, delete useless users"

(2)

Groupadd # #建立用户组

GROUPADD-G Student # #建立用户组并且指定用户组的初始组id

Groupdel # #删除用户组

(3) Change of user information

Usermod

Usermod-l new name Student # #更改用户新名称

Usermod-u 6666 Student # #更改用户uid

USERMOD-G Student # #更改用户的初始id

Usermod-g Student # #更改用户的附加组 (if you have an additional group, then use-G will change the original additional group)

Usermod-ag Student # #添加用户的附加组, if there is an additional group in it, a new additional group is appended later

Usermod-g "" Student # #删除用户所有附加组

Usermod-c "abc" Student # #更改用户的说明文字

usermod-d/home/lsy Student # #更改用户家目录的指向

Usermod-md/home/lsy Student # #更改用户家目录

Usermod-s/bin/sh Student # #更改用户的shell

Usermod-l Student # #冻结用户

Usermod-u Student # #解锁用户

6. User password settings passwd student [the system in this password does not interact with the consumer, which improves security]

Two. User authentication information Management

1. Certification Information file

The user's authentication information is recorded in/etc/shadows, which includes:

(1) User name:
(2) User password:

passwd Student
Passwd-l student # #在用户密码前加入 "!! ", similar to freezing
Passwd-u Student # #解锁密码
passwd-d Student # #清空student密码
Usermod-l student # #在用户密码前加入 "! ”
Usermod-u Student # #解锁用户

(3) The time the user password was last changed:

PASSWD-E Student # #会改变用户最后一次更改密码的时间为0, users will be forced to change their password upon login

chage-d 0 Student # #两个命令功能相似
(4) Minimum password period:

Passwd-n 1 Student # #student用户在一天之内不能更改密码

Change-m 1 Student # #同上

(5) Maximum password period:

Passwd-x Student # #student在30天内必须更改密码

Change-m Student # #同上

(6) Password warning period:

Passwd-w 2 Student # #密码过期前两天有警告输出

Change-w 2 Student # #同上

(7) The password is inactive

Passwd-i 1 Student # #密码过期后仍可登录系统的天数

Change-i 1 Student # #同上

(8) Password expiry date

CHAGE-E 2018-11-11 Student # #student用户在2018-11-11 will be frozen

(9) User-defined columns (cannot be manipulated)

Three. User authorization

User Authorization Profile/etc/sudoers
Authorization configuration command: Visudo This syntax will have syntax errors compared to VIM
Hostname View host (native) name

Linux from Getting started to mastering-user management