An efficient way to transpose a file in Bash

Question

I have a huge tab-separated file formatted like this

X column1 column2 column3
row1 0 1 2
row2 3 4 5
row3 6 7 8
row4 9 10 11

I would like t

Answer 1

An awk solution that store the whole array in memory

    awk '$0!~/^$/{    i++;
                  split($0,arr,FS);
                  for (j in arr) {
                      out[i,j]=arr[j];
                      if (maxr

But we may "walk" the file as many times as output rows are needed:

#!/bin/bash
maxf="$(awk '{if (mf

Which (for a low count of output rows is faster than the previous code).