Linux Classroom essay---fourth day

User Account Profile

in the The Linux system has three categories of users, namely root user, System user and ordinary user.

in the Linux System, theroot user UID is 0,root The user's permissions are the highest, the ordinary user cannot perform the operation,theroot user can complete. So it is also called super User.

All apps create a user at the time of installation, which is the system user (background service account)UID 1-499

ordinary users, can log on the system, in Linux System can do ordinary work, can operate their own directory content, its use of the system is restricted, such users are created by the system administrator. Its UID is 500-60000

The Passwd file is an important file for system-aware users, and All users in the Linux system are logged in the file.

any user can read etc/passwd

in the The root Uid of the Linux system is 0and has the highest system privileges.

Shadow is a Shadow file for file etc/passwd. Includes information that the user and the encrypted password and other etc/passwd cannot include.

Create a user account

Useradd Zhangsan

Modify user Account

Usermod

Delete User

Userdel Lisi

Group account Classification

Private Group  Standard Group Main group Secondary Group

Private Group When creating a new user account, if you do not specify which group the user belongs to, then Linux creates a group that has the same name as the user, which is the private group, which is the only user in this private group.

Standard Group also known as a common group, can contain multiple user accounts, if you use a standard group, then when creating a new user account, you should specify which group the user belongs to.

The other is to divide the group into primary and secondary

Main group

When a user account belongs to more than one group member, the group that belongs to after landing is the main group, the other group is a secondary group, and a user account belongs to only one main group.

Create a group

Groupadd China

Modifying a group

Groupmod

View the members of the group that the user belongs to

Groups AB

Id

use the ID command to display the UID of the user and the GID of the group to which the user belongs

Su

You can use the SU command to switch to another account to log in. If su does not add any options, the default switch to the root user does not change the Shell

Sudo

Linux Classroom essay---fourth day