Code:
alias readwrite {   
  var %i = 1    
  while (%i <= $lines(test.txt)[color:red])[/color] {     
    write example.txt $read($mircdirtest.txt,%i)   
    inc %i  
  }
}


Test1.txt contains:
T
Te
Tes
Test
Testi
Testin
Testing

Test2.txt was created and now contains:

T
Te
Tes
Test
Testi
Testin
Testing