amerge: call a program with different inputs and merge the outputs of the
  subsequent calls (1st line of the first command, 1st line of the 2nd command,
  2nd line of the 1st command and so on).

Parameters:
-p [param]: the 'param' wil be forwarded to the client program

Examples:
amerge -p dir1 -p dir2 afind "*.txt" -root PARAM
  -> the afind will be called two times, first the 'dir1' value in 'PARAM',
     then with 'dir2' replaced in 'PARAM'.