Add functionality for the following:

userdel -G
remove user from group
groups
list all groups in order. Not in tabulated form
groupadd
create a new group
usermod -a -G
add current user to group
useradd -G <group1,group2,...groupn>
add specified user to all groups listed. Comma delineated
useradd
create a new user. Should add user to default group
userdel
delete the specified user
switchto
change current user to the user specified
./
execute the program/file
chown
change the owner of the file specified to the user specified
chgrp
change the group of the file specified to the group specified