LINUX Redhat Fifth Unit documentation

I. User understanding
The user is the identity of the system consumer
The user is stored in the system as a number of channeling characters + several system configuration files
User information involves the system configuration file:
/ETC/PASSWD # # #用户信息
User: Password: uid:gid: Description: Home directory: User-used Shell
/etc/shadow # # #用户认证信息
User: Password: Last password modified this time: Minimum validity: Maximum validity: Warning Period: Inactive period: Account expiration date
/etc/group # # #组信息
Group name: Group password: Group ID: Additional Group member
/etc/gshadow # # #组认证信息
/home/username # # #用户家目录
/etc/skel/.* # # #用户骨架文件650) this.width=650; "Src=" https://s1.51cto.com/wyfs02/M00/8F/8A/ Wkiom1jkgjgdzhj7aaif8az1fza638.png-wh_500x0-wm_3-wmp_4-s_3227701314.png "title=" Screenshot from 2017-03-25 09-21-45.png "alt=" Wkiom1jkgjgdzhj7aaif8az1fza638.png-wh_50 "/>

Two. User Management


1. User Establishment
Useradd parameter User name
-U # #指定用户uid
-G # #指定用户初始组信息, this group must already exist
-G # #指定附加组, this group must exist
-C # #用户说明
-D # #用户家目录
-S # #用户所使用的shell,/etc/shells records the name of the user who can use the shell

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2. User Delete
Userdel-r User name-R means delete user information and user's system configuration

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3. Establishment of groups
GROUPADD-G # #建立组
Groupdel Group Name # #删除组
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Watch-n 1 ' tail-n 3/etc/passwd/etc/group;echo ====;ls-l/home;echo ===;ls-l/mnt '


4. User ID Information view
ID parameter user
-U # #用户uid
-G # #用户初始组id
-G # #用户所有所在组id
-N # #显示名称而不是id数字
-A # #显示所有信息

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5. User information changes
usermod     parameters      Users
    -l    # #更改用户名称
    -u    # #更改uid
     -g    # #更改gid
    -G    # #更改附加组
     -ag    # #添加附加组
    -c    # #更改说明
    -d     # #更改家目录指定
    -md    # #更改家目录指定及家目录名称
    -s     # #更改shell
    -L    # #冻结帐号
    -U    # #解锁

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Three. User decentralization

1. Power Users in the system can delegate actions that ordinary users cannot perform to the normal user
Delegating power profile:/etc/sudoers

2. Methods of decentralization
*) Super User execution Visudo enter edit/etc/ Sudoers Mode
*) format:
Get rights user      Host name = (acquired user identity)      command
test     desktop0.example.com= (Root)     /usr/sbin/useradd
Test user can execute/usr/as Superuser in desktop0.example.com Sbin/useradd

3. Implementation of the delegation of authority command
sudo command # #如果第一次执行sudo需要输入当前用户密码
In/etc/sudoers if the settings are as follows:
Test desktop0.example.com= (Root) nopasswd:/usr/sbin/useradd
Indicates that the user does not need their own password when invoking the sudo command

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Four. Control of user authentication information

Chage parameter User
-D # #用户密码组后一次修改的时间, if set to 0, users must change their password after logging into the system
-M # #最短有效期
-M # #最长有效期
-W # #警告期
-I # #用户非活跃天数
-E # #帐号到期日格式-E "Yyyy-mm-dd"

LINUX redhat Fifth Unit document