Linux lid (libuser-lid) Command Examples

Originally published at: https://www.cyberciti.biz/faq/linux-lid-command-examples-syntax-usage/

lid command
I am a new Linux and Unix system user. How do I list the user’s groups or group’s users on Linux operating systems? How can I show list of users belonging to a given group on Linux based server?

You can use passwd file and group file.
/etc/passwd
/etc/groups