Summary of four user management for study notes of destiny LINUX

 

There are three types of users in linux:

1: The Super User root has the permission to operate everything. The UID value is 0.

2: normal user: UID 500---60000 with limited operating system Permissions

3: pseudo-user: to facilitate system management and meet the requirements of the owner of the corresponding system process file, you cannot log on between UID 1---499.

 

User Management: passwd/etc/passwd defines only accounts, not passwords.

Example: root: x: 0: 0: root:/bin/bash

Six: The number is divided into seven parts

Root: Account name

X: indicates a password.

0: User ID (User ID)

0: Group id (User Group id)

Root: user information.

/Root user's home directory

User Environment:/bin/bash

Using echo $ SHELL to view the SHELL in which the user group is located

Create user: useradd zlyzhang

Passwd zlyzhang

Vi access

/Etc/shadow. Only the root user can read this file and it is composed of nine fields separated by a colon.

For example:

Root: User example

Root: $1 $6Xv8mUT1 $ IzPlyczUKcCPYqQwptnvw1: 14982: 0: 99999: 7 :::

Nscd :!! : 14982: 0: 99999: 7 :::

Username: root

Password: stores the encrypted password. If the first character of the password is! Exclamation point, the user cannot log on

Last modification time

Maximum time interval: 0 indicates changes at any time

Minimum interval: 99999 indicates that the device never expires.

Warning time: 1 week

No activity time:

Expiration time:

User Account Management:

Command to create an account: useradd account or adduser-u-g-G-d-s-c-e-k-n-N-r has these Command Options

Passwd Password

 

Delete user; userdel account

If the file in the userdel-r account's home directory is deleted,

----------------

Change Username:

Example: useradd redhat

Passwd lamp

Account Created successfully: You need to change the username,

Usermod-l zhangluya redhat

In this case, you can change the user login name.

---------------------------------------------------------------------------

Locked account: usermod-L thisuser

Unlock: usermod-U thisuser

Stop account: Add # (the beginning of the first line) before the account line, but it is different from deleting files. Comment out.

Password Management:

Passwd-S (uppercase) redhat to view the password status:

Passwd-l destiny password locked

Passwd-u destiny unlock Password

---------------------------------------------------------------------

Add: Specify the group at creation: useradd-g ttt kkkkk

Kkkk users are in the ttt Group

 

Passwd press enter to change the current user password

If you want to change the password of another user:

Passwd username

Switch user identity: su username

Switch su-username to the user's home directory

-D directory: Specifies the user's main directory. If this directory does not exist, you can use the-m item to create a main directory.

-G user group: Specifies the user group.

-G User Group specifies the user's additional group useradd-g root-G linux Jesse

-U user number, specifying the user number

Example:

Useradd-d/usr/edu

Create a user edu

Here,-d is used to generate a main directory/usr/edu for the login name edu (/usr is the parent directory of the default user main directory)

Delete user: When userdel-r Jesse deletes a user, the user's home directory is also deleted.

User Password Management:

Passwd-d redhat

The redhat user does not need a password when logging on.

Locked account:

Passwd-l redhat so that users cannot log on

Lock -- l

Unlock: passwd-u redhat

U = unlock

 

Add group:

Groupadd redhat

/Etc/group is saved here

Delete group: groupdel redhat

 

This article is from the "jesse's blog" blog