Comparing and Merging Files
10.3 Applying Imperfect Patches
patch tries to skip any leading text in the patch file,
apply the diff, and then skip any trailing text. Thus you can feed a
mail message directly to
patch, and it should work. If the
entire diff is indented by a constant amount of white space,
patch automatically ignores the indentation. If a context
diff contains trailing carriage return on each line,
automatically ignores the carriage return. If a context diff has been
encapsulated by prepending `- ' to lines beginning with `-'
as per Internet RFC 934,
patch automatically unencapsulates the input.
However, certain other types of imperfect input require user
intervention or testing.