Linux Advanced Commands (IX): User-related operations, to know to create user commands

User-related operations

learning target

• Create a user can know the command

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1. Create a user

command	Explanation
useradd	Create (add) a user

useradd command options:

Options	Explanation
-m	Automatically create the user's home directory, home directory name is the user name
-g	User group the user belongs, do not specify the default will automatically create a user group with the same name

Create a user renderings:

View all user information file renderings:

Description:

• useradd use the command requires administrator privileges, front need to add sudo
• If you do not specify a user to create a user group, the default will automatically create a user group with the same name
• Check whether the user has been created, you can view ** / etc / passwd ** This file
• View user group is created, you can check ** / etc / group ** This file

Each information Description passwd file to root❌0: 0: root: / root: / bin / bash as an example:

• First: Username
• Second: Password placeholder
• Third: uid, user id
• Fourth: gid, user's group id
• Fifth: user description, optional
• Sixth: the location of the user's home directory
• Seventh: The type of shell with a user, typically a bash or sh, sh type is not set by default

Each group file description information to laowang❌1001: for example:

• The first one: User Group Name
• Second: password placeholder user groups, user group Linux system generally do not have a password
• Third: the group id

id command to view the user information:

command	Explanation
id	View user information

id command renderings:

each item of information Description:

uid = 1001 (laowang) gid = 1001 (laowang) group = 1001 (laowang)

• The first: uid represents the user id
• Second: gid indicating the user group id
• Third: Group means that the user where the user group

2. Set password

Other users to set a password, use: sudo passwd username

Password renderings:

3. Switch user

command	Explanation
his	Switch User

Syntax: su - username

FIG handover user effects:

In laowang user sudo -s renderings:

Solution:

• Laowang provided to a user sudo additional group is required to modify the user information usermod

4. Modify User Information

command	Explanation
usermod	Modify user information

usermod options:

command	Explanation
-G	An additional group settings
-g	Modifying User Groups

usermod command renderings:

After setting additional groups sudo, the switch to an administrator sudo -s FIG user effects:

5. Expansion: delete additional groups

command	Explanation
gpasswd	Add and remove additional group information

gpasswd command options:

Options	Explanation
-a username	To add additional user groups
-d username	To delete additional user group

Delete additional groups renderings:

Delete additional group again using sudo -s renderings:

5. Delete User

command	Explanation
userdel	delete users

userdel command options:

Options	Explanation
-r username	Delete the user's home directory must be set, otherwise the user's home directory will not be deleted

Delete User renderings:

View user id information renderings:

View group file information renderings:

Description:

• Delete a user, the default user group with the same name will be deleted

6. Summary

• Create a user command format: sudo useradd -m user name , the default will create a user group of the same name.
• View user information using the id command or / etc / passwd file
• View user group information using the / etc / group file
• To the user password using sudo passwd user name
• Switch users using su - username
• Set up additional groups using sudo usermod -G group name Username
• Delete users sudo userdel -r user name , the same name as the default user group will be deleted.