perl, 59 bytes

Result

AC

Duration

727ms

Code [DL]

$_=`dd`;/T/;s/^.{$-[0]}\K /T/mg;s/K */K x length$&/ge;print

stdin

               T                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
       K                                          

stdout

               T                                  
               T                                  
               T                                  
               T                                  
               T                                  
               T                                  
               T                                  
               T                                  
       KKKKKKKKT                                  

stderr

0+1 records in
0+1 records out

strace