awk help needed please

I'm writing an awk program to parse an /etc/passwd file that contains records like:

jones::100:100:John Jones:/usr/bin/csh
fred::200:0:Fred Franklin:/usr/bin/csh
bob::300:100:Bob Smith:/usr/bin/csh
jjones::600:100:John Jones:/usr/bin/csh
admin::200:100:Fred Franklin:/usr/bin/csh
useless::200:0::/usr/bin/csh
...

From this file I created another file named "names" using cut and egrep that contains the 5th field from /etc/passwd and gets rid of blank lines, which looks like:

John Jones
Fred Franklin
Bob Smith
John Jones
Fred Franklin

Now, I'm trying to use awk to examine each line of the /etc/passwd file and calculate the following:
- total number of records in /etc/passwd
- % of records that are duplicates
- print the duplicate users (their full name) and how many entries in /etc/password each dupe user has.

So I'm using the "names" file to create an associative array called users_array, but I am completely stuck after that point. Here is what I have so far, any help would be greatly appreciated!! :

BEGIN {
while ( getline var<"names" ) {
users_array[var]=0;
print var;
print users_array[var];
}
}
# this is a lot harder than perl in my opinion
# for each name process each line in /etc/passwd

END {
print FILENAME
}
#print output

try something liek this - I can't test this but it should be close:

Your problem is not too complicated. You do not need generate the "names" file, because all can be done in memory. You must only read the /etc/passwd twice in one awk script. Take following as my Xmas present:

:
awk '
BEGIN {

# Extract all user names
FS = ":" # Use this field separator
TNR = 0 # Initialize total number of records
I = 0 # Initialize counter
while (getline < "/etc/passwd" > 0) {
TNR++
if ($5 != "") # The name given?
USER[++I]=$5
}
N=I # Total number of records with unempty name field
close ("/etc/passwd")

# Reread /etc/passwd and process it
while (getline < "/etc/passwd" > 0) {
if ($5 != "")
DUP[$5]++ # Remember this user's count of duplicates
}
close ("/etc/passwd")

# Generate the output
ND = 0 # Initialize number of duplicates
for (U in DUP) {
if (DUP[U] > 1) {
printf "duplicate: %s - %d times\n", U, DUP[U]
ND++
}
}
printf "total number of records %d\n", TNR
printf "total number of named records %d\n", N
printf "percent of duplicates: %10.2f\n", 100* ND/N

exit 0 # The end
}
'

Perl is realy better, but it is a "write only language". One cannot decipher his own code...
(Tested on Linux)