~$ cat old
#コメント
nullpo='ガッ'
~$ cat new
#comment
nullpo='ガガガ'
~$ diff -p old new
*** old 2018-05-21 20:48:21.658068575 +0900
--- new 2018-05-21 20:45:14.981142894 +0900
***************
*** 1,2 ****
! #コメント
! nullpo='ガッ'
--- 1,2 ----
! #comment
! nullpo='ガガガ'
~$ diff -p old new > patch-file
~$ patch < patch-file
patching file old
~$ cat old
#comment
nullpo='ガガガ'
~$ cat new
#comment
nullpo='ガガガ'
~$ diff old new
~$