Linux User Creation and permission-related operation demonstration, linux operation demonstration

Linux User Creation and permission-related operation demonstration, linux operation demonstration
Basic command operations

The procedure is as follows:

Groupadd testgroupuseradd-d/usr/test-g testgroup-m testuserpasswd testuser # query user group # groups cpic # delete user # userdel cpic

Questions

The password is too short to be modified

How to change the user password in CentOS

Problem:

Invalid password: too short

Invalid password: Too simple

Invalid password: it is based on dictionary words

Solution:

1. Common users

A. Obtain the root permission of a Super User

Command: su, su-, or su-root

B. passwd User Name

2. superuser

A. Open the system-auth file.

Command: vi/etc/pam. d/system-auth

B. modify one line (set the minimum password length to 4 ):

Password requisite pam_cracklib.so try_first_pass retry = 3 type = minlen = 4

C. passwd Super User Name

Unable to obtain permissions for some Directories

Because directory B has the permission to drwxr-xr-

There are two solutions for each layer of directories:

1) make user1 the owner of the Directory

2) The directory owner is still root, but the permission is changed to xxx r-x, so that non-root users can access and read.

Reference

[1]. How to change the user password in CentOS?

[2]. In linux, you can only Log On As A guest user. you can log on as a root user or as a non-root user.

[3]. Directory Access Permissions for common users in Linux

[4] viewing all users and all user groups in Linux