Shell Programming and Scripting

Hey all,
i have to write a script in Unix that would help me in my department to search certain user ids valid in /etc/passwd file.. here goes the exact question & data to help analyze:
Amend a script to tell the user to enter a user id to be searched for in the /etc/passwd file. If there are no matches a message is given to
the user. If there is a single match echo the user name, user ID and group ID.
cat /etc/passwd
nhamilto:*:3356:102:Nichole Hamilton:/home/student/nhamilto:/bin/csh
khenders:*:3357:102:Kelsey Henderson:/home/student/khenders:/bin/csh
rruby:*:3358:102:Reidgem Ruby:/home/student/rruby:/bin/csh

I recommend using $? And if-then-else but cant come up with something solid to built my script on... i'll be very thankful if u could help me out someway..
thanks

can you use the finger command?

Code:

$ whatis finger
finger               (1)  - user information lookup program

echo "Please input the user name"
read name
cat /etc/passwd | nawk -F":" -v name="$name" '{
if ($1==name)
{
print $1," ",$3," ",$4
flag=1
}
}
END{
if (flag==0)
print "not a valid account"
}'

ypcat passwd | grep <userid>

or

getent passwd <userid>

Thanks Frank for the reply..Im afraid i cant use finger command yet...Im even not aware of its use...but in future i think it would ease my solutions..
Ya Thobias this would work if it is given in one line command at $ prompt but then i must write a script...so there are whole lot of more steps that i have to incorporate.. but this is easy when i need instant answer..thanks a lot for help...much appreciated

U r genius!! thanks a lot summer_cherry... my job was on line for this..almost atleast... this works perfectly fine.. i have 4 more of this type..
namely one how do i amend the same script to reply with the number of matches if there are multiple results from the search using "case" option

What you meant to say is: "My grade was on the line for this. I have 4 more homework problems of this type....."