join command means Join lines of two files on a common field.

Syntax
join [OPTION]… FILE1 FILE2
In man page the describe it
- join – join lines of two files on a common field.
- man join – More details information about join
command .
join command in Linux with Examples
$ join huuphan.txt devopsroles.txt
Conclusion
join command is the simple the command in Linux. It is the most popular in use terminal Linux join lines of two files on a common field.