#!/bin/bash
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# Title       : CS576 Assignment 1: umail                                      #
# Name        : Woodrow H. Edwards                                             #
# Date        : 20091007                                                       #
# Description : Unix Accounts Mailing Lists                                    #
################################################################################

# if no parameters are passed, set positional parameters to standard group list
[ $# -eq 0 ] && set student faculty grad staff guest

# for every group in the positional parameter list
for g; do
	# extract the group number for the group from field 3 of group file
	gn=$(ypcat group | awk -F: -v g=$g '$1==g {print $3}')

	# list user name (field 1) and full name (field 3) from the passwd file
	#  if the primary group number (field 4) matches
	ypcat passwd | awk -F: -v gn=$gn '$4==gn {print $1 ":" $5}' > ${g}Names

	# extract just the user name from previous
	cat ${g}Names | awk -F: '{print $1}' > ${g}Emails
done