Big Data and cloud computing (Wang Minglong) instructor-linux-day01-User Management

User Management

A Must know Point
1. User Information file/etc/passwd
2. User name: Password: uid:gid: Description Information: Home directory: Login status
3. User Password storage file/etc/shadow
4. Every time a new account is created, a home directory with the same name as the username will be generated in the home directory

Two Add an Account

Useradd The name of the "parameters" account

-U Specify UID usage for User: useradd-u UID Number user name
-G Specify the user's primary group usage: USERADD-G Group name User name
-G Specify user's attached group usage: USERADD-G Group name User name
-D Specify the user's home directory usage: useradd-d/directory name User name
-s Specifies that the system cannot be logged on user usage: useradd-s/sbin/nologin user Name

Three Switch users

SU user name only switches users, not fully logged inSu-user name fully logged into userExit Log out of your current account

Add an account manually (to speak)

Four Modify your account (you can directly modify the passwd file)

Usermod–helpusermod-l new name Old name//modify user nameusermod-u New ID User name//modify User ID numberusermod-u New Id-o username//Add an already existing UIDusermod-g new GID username//Modify user's group ID numberusermod-c Account Description User name//Add descriptive information to the userusermod-d Home directory path user name//modify user home directoryusermod-s New Shell username//Modify user's shell, also known as Modify user's login statususermod-s/sbin/nologin username//Modify user cannot login systemusermod-g Group name User name//modify user's attached groupusermod-l User name//lock userusermod-u user name//unlock user

See which shells are now supported by the system:

Cat/etc/shells

Five Delete Account

userdel-r User name/delete user at the same time delete personal informationUserdel User name//delete User only

Six Account password Settings password: Normal account can not set their own initial password, can only modify

passwd//Modify the current login account passwordpasswd User name//modify the password of the specified user

Seven Lock password//only root can operate

passwd-l account name//Lock account passwordpasswd-u account name//Unlock account passwordpasswd-s Account name//view user status

User Group Management

A Must know Point
1. User group information file/etc/group Group name: Representative Group Password: GID: Team member
2. User group password storage site/etc/gshadow Group name: encryption Password: Group Administrator: Team members

Two Add Group

Groupadd Group name//Add group, GID system automatic assignmentgroupadd-g GID Group name//modify group IDgroupadd-g gid-o Group name//Plus-o parameter, can add n GID same group

Three Modify Group

groupmod-n New group name old group name/modify Group namegroupmod-g GID Group name/modify GIDgroupmod-g gid-o Group name//Plus-o parameter, can be modified to a group of n GID same

Four Delete a group

Groupdel Group name

Five Group password

GPASSWD Group name

Six Add and remove members

gpasswd-a account name Group name//Add team membergpasswd-d account name Group name//delete team member

Seven Add Group Admins

gpasswd-a User name Group name

Eight Modify file attached Group

CHGRP Group name file name key content

Big Data and cloud computing (Wang Minglong) instructor-linux-day01-User Management