How to use 'readarray' in bash to read lines from a file into a 2D array

Question

Let\'s say I have a text file \'demo.txt\' who has a table in it like this:

1 2 3    
4 5 6    
7 8 9    

Now, I want to read each line separat

Answer 1

readarray rows < demo.txt                                           

for row in "${rows[@]}";do                                                      
  row_array=(${row})                                                            
  first=${row_array[0]}                                                         
  echo ${first}                                                                 
done