Linux advance commands
#useradd- creating user account
#groupadd- used to create user groups
#gpasswd- adding members to group
#sudo cat /etc/group - to see the number of groups available
#chgrp-to change the owner of the group
chmod-used to change access permissions for file/director
Refer below file permissions
chown-To change the ownership of the file
#grep -to find the find particular file or string in a file