chown command helps you to change file and/or directory ownership in Unix.
IMPORTANT: chown needs to be run as root.
As root user, let's create a file named "try":
[root@rhel8 /home/greys]# touch try
it belongs to user root and group root:
[root@rhel8 /home/greys]# ls -al try -rw-r--r--. 1 root root 0 Feb 20 06:44 try
change ownership to user greys and group wheel
[root@rhel8 /home/greys]# chown greys:wheel try [root@rhel8 /home/greys]# ls -al try -rw-r--r--. 1 greys wheel 0 Feb 20 06:44 trl