Linux User Management and linux User Management

Linux User Management and linux User Management

1. view existing users in Linux:

[Root @ CMCC_91 ~] # Cut-d:-f 1/etc/passwd

[Root @ CMCC_91 ~] # Cat/etc/passwd | awk-F \: '{print $1 }'

2. You can view the users you want to view through pipelines:

Filter the query results using pipelines: [root @ CMCC_91 ~] # Cat/etc/passwd | awk-F \: '{print $1}' | grep expression.

3. view the logon records of a specified user:

[Root @ CMCC_91 ~] # Last | grep expression; (LOGIN successful user)

[Root @ CMCC_91 ~] # Lastb | grep expression; (unsuccessful logon user)

4. view the information of a single user:

[Root @ CMCC_91 ~] # Finger username; (view the user's login information and directory)

[Root @ CMCC_91 ~] # Id username; (view the group information that the user belongs)

5. view the current user login:

[Root @ CMCC_91 ~] # W

[Root @ CMCC_91 ~] # Who

[Root @ CMCC_91 ~] # Whoami

6. Create a user:

[Root @ CMCC_91 ~] # Useradd [option] username;

Option:

To view all the options, run [root @ CMCC_91 ~] in shell. # Useradd -- help; (the following are some of the most common ones)

-D specifies the login directory of the current login user (that is, after the user logs on, execute cd ~ Directory)

-M: If the logon directory specified by-d does not exist and this attribute is added, the logon directory is automatically created.

-M: do not automatically create a user's logon directory.

-G: Specifies the user group to which the user belongs.

7. delete a user:

[Root @ CMCC_91 ~] # Userdel [option] username;

Option:

To view all the options, run [root @ CMCC_91 ~] in shell. # Userdel -- help; (The following describes several common ones)

-R: the home directories of the users to be deleted are also deleted.

8. Modify existing users:

[Root @ CMCC_91 ~] # Usermod [option] username;

Option:

To view all the options, run [root @ CMCC_91 ~] in shell. # Usermod -- help; (most of them use the options of useradd. The following describes several frequently used options)

-L modify the username of the user

9. User Password Management:

A newly created user cannot log on without a password (This section describes how to set a password for a new user ):

Super Users can specify passwords for themselves and other users. Common users can only use them to modify their own passwords:

[Root @ CMCC_91 ~] # Passwd [option] username;

Option:

To view all the options, run [root @ CMCC_91 ~] in shell. # Passwd -- help; (The following describes some of the more common ones)

For example, modify the password of the current user:

$ Passwd
Old password :******
New password :*******
Re-enter new password :*******