Shell Programming and Scripting

//class1.txt
45
234
67
89
90
//class2.txt
456
34
78
89
120

67 9
89 5
234 9

456  9
120  12

67 9
89 5
234 9
45  0
90  0

456  9
120  12
34   0
78   0
89   0

awk '
        /^\// {
                sub ( "//", X )
                F[$1]
                f = $1
                next
        }
        !/^\// {
                R[f","$1]
        }
        END {
                for ( k in F )
                {
                        while (( getline line  < k ) > 0 )
                        {
                                split ( line, V )
                                T[V[1]] = V[2]
                        }
                        for ( j in R )
                        {
                                split ( j, V, "," )
                                if ( V[1] == k )
                                        M[V[2]]
                        }
                        for ( l in M )
                        {
                                if ( l in T )
                                        print l, T[l] > k
                                else
                                        print l, "0" > k
                        }
                        close ( k )
                        split ( "", M )
                        split ( "", T )
                }
        }
' file.txt