UNIX for Dummies Questions & Answers

awk -F= '
        BEGIN {
                j = 1
        }
        NR == FNR {
                T[$1]
                next
        }
        !flag {
                for ( k in T )
                        S[k] = ++c
                flag = 1

        }
        {
                if ( S[$1] < S[p] )
                        ++j
                A[$1,j] = $2
                p = $1

        }
        END {
                for ( k in S )
                        s = s ? s OFS k : k
                print s
                s = ""
                for ( i = 1; i <= j; i++ )
                {
                        for ( k in S )
                                s = s ? s OFS A[k,i] : A[k,i]
                        print s
                        s = ""
                }
        }
' OFS=, file file

awk -F"="       'BEGIN  {print "a,b,c,d";}
                 /a/    {if (NR>1) print A,B,C,D; A=B=C=D=""; A=$2}
                 /b/    {B=$2}
                 /c/    {C=$2}
                 /d/    {D=$2}
                 END    {print A,B,C,D}
                ' OFS="," file
a,b,c,d
1,2,3,
4,2,,3
3,,4,