copy the last part of a file

-f     If the input file is a regular file or if the file operand specifies  a  FIFO,  do  not  terminate
       after  the  last  line of the input file has been copied, but read and copy further bytes from the
       input file when they become available. If no file operand is specified and  standard  input  is  a
       pipe,  the  -f option shall be ignored. If the input file is not a FIFO, pipe, or regular file, it
       is unspecified whether or not the -f option shall be ignored.