/etc/passwd ⇒ user
/etc/group ⇒ group
/etc/shadow ⇒ password
Generally, the following sequence is used to create groups and users for the system
Create User -> Create Group -> Add User to Group -> Create Password
Example:
1. Create two groups
groupadd -g 6000 batch
groupadd -g 2018 tomcat
groupadd -g 22000 sabopeusr0
2. Create user
useradd -u 6000 -g 6000 -d /home/batch -s /bin/bash batch
useradd -u 2018 -g 2018 -d /opt/tomcat -s /sbin/nologin tomcat
useradd -u 22001 -g 22000 -d /home/sabopeusr0 -s /bin/bash sabopeusr0-admin
3. Add user to group
gpasswd -a batch tomcat
gpasswd -a tomcat batch
gpasswd -a sabopeusr0-admin wheel
4. Use chpasswd to add passwords in batches (note that if an error occurs again in the middle, it is best to execute it again)
First create a user password corresponding file, the format is username:password, such as abc:abc123, it must be written in this format,
and there can be no blank lines, save it as a text file user.txt, and then execute the chpasswd command:
chpasswd < user.txt
5. Modify a user's password
passwd sabopeusr001 individually