-b     Cause any amount of white space at the end of a line to be treated as a single <newline> (that is,
       the  white-space  characters preceding the <newline> are ignored) and other strings of white-space
       characters, not including <newline>s, to compare equal.

-c     Produce output in a form that provides three lines of context.

-C n   Produce output in a form that provides n lines of context (where  n  shall  be  interpreted  as  a
       positive decimal integer).

-e     Produce  output  in a form suitable as input for the ed utility, which can then be used to convert
       file1 into file2.

-f     Produce output in an alternative form, similar in format to -e, but not intended to be suitable as
       input for the ed utility, and in the opposite order.

-r     Apply  diff  recursively  to  files and directories of the same name when file1 and file2 are both
       directories.