a1667203

command

% cat >patchtest.old
aaa
bbb
ccc
% cat >patchtest.new
aaa
xxx
ccc
% ls
patchtest.new  patchtest.old  patchtest.txt
% diff patchtest.old patchtest.new 
2c2
< bbb
---
> xxx
% diff -c patchtest.old patchtest.new 
*** patchtest.old	2008-09-09 20:53:01.000000000 +0900
--- patchtest.new	2008-09-09 20:53:17.000000000 +0900
***************
*** 1,3 ****
  aaa
! bbb
  ccc
--- 1,3 ----
  aaa
! xxx
  ccc
% diff -c patchtest.old patchtest.new >patchtest.patch
% patch <patchtest.patch 
patching file patchtest.old
% diff patchtest.old patchtest.new   
% 

note

cf.
% man patch
% man diff