merge-auth.rb

p1 = open("passwd").read.split("\n")
s1 = open("shadow").read.split("\n")
s1.delete_if { |ent| ent.split(":")[1] !~ /^\$1\$/ }
shash = Hash[*s1.collect { |e| [e.split(":",2)[0],e.split(":",2)[1]]}.flatten]
phash = Hash[*p1.collect { |e| [e.split(":",2)[0],e.split(":",2)[1]]}.flatten]

newpasswd = open("/tmp/passwd").read
phash.each { |k,v|
        unless newpasswd.split("\n").include?(k + ":" + v)
                if shash.has_key?(k)
                        newpasswd << k + ":" + v + "\n"
                end
        end
}
newshadow = open("/tmp/shadow").read.split("\n")
s1.each { |e|
        unless newshadow.include?(e)
                newshadow << e
        end
}
puts newshadow.join("\n")

open("/tmp/shadow",'a') {|f| f.write(newshadow.join("\n")) ; f.write("\n")}