Shell Programming and Scripting

1231231231 3 A
4561223343 0 D
1231231231 1 A
1231231231 2 A
1231231231 4 D
7654343444 2 A
4561223343 1 D
4561223343 2 D

1231231231 3#1#2 A
4561223343 0 D
1231231231 4 D
7654343444 2 A
4561223343 1#2 D

$ cat lmerge.awk

# Only run the code inside the bracket if $2 is nonzero.
$2 {
    # Append second column to array with index like "1231231231,D".
    # Value gets stored like #1#2#3#4.  We'll chop off the first # later.
    A[$1","$3]=A[$1","$3] "#" $2
    # Print this line directly if $2 is zero.
    } ! $2

END { # Print the contents of the array, chopping the index X into V[1]="1231231231",
       # V2="D", skipping past the first character of A[X], and printing in the order we want.
        for(X in A)
        {
                split(X, V, ",");
                print V[1], substr(A[X],2), V[2];
        }
}

$ awk -f lmerge.awk < data

4561223343 0 D
4561223343 1#2 D
1231231231 3#1#2 A
7654343444 2 A
1231231231 4 D