New Linux users may encounter problems when users are added or deleted in linux.

New Linux users may encounter problems when users are added or deleted in linux.
Problems that new users may encounter when adding or deleting users in Linux

1. After creating a new user, switch to the new user: No directory, logging in with HOME =/

Add User # sudo useradd-m-s/bin/bash-g group loginname-m to create the home directory (if this is not added, manually add the directory, otherwise No directory appears, logging in with HOME =/)-s/bin/bash use bash (the default value is/bin/sh. By default, loginname @ ubuntu is not displayed before $) -g group and then use passwd to change the User Password

2. When deleting a user: userdel: user hbase is currently logged in

Or: userdel: user test is currently used by process 2417 userdel: cannot open/etc/subuid
Many solutions on the Internet are as follows:
$ Mv/var/run/utmp _
$ Touch>/var/run/utmp
About:/var/run/utmp
Utmp is a file. You cannot edit the file except the utmp program. If you delete the file, the current login information will be lost.
This file will be re-created every time the machine is reboot.

However, if I tried it myself, I still got the same prompt.
Delete the user as follows:

$ Userdel-r-f XXXX
Tip: userdel: warning: can't remove/var/mail/git: No such file or directory
Userdel: git home directory (/home/git) not found
But it does not matter. The user has been deleted successfully.

As shown in:

Linux User deletion Problems

This indicates that when you delete a user, it is not completely deleted. There are also some traces of the original user. To completely delete a user, use the following method:
Userdel-r <username>

In linux, how does one delete a user from a group?

To delete a user from a group, follow these steps:
Edit/etc/group, locate the GROUP1 line, and delete
Or use the command

Gpasswd-d A GROUP

Add the following workgroup to existing users:
Usermod-G groupname username
Or: gpasswd-a user group
Reference: blog.sina.com.cn/s/blog_a6dcb5bd01017d0x.html