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(diff.info)Invoking diff

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Invoking `diff'
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   The format for running the `diff' command is:

     diff OPTIONS... FROM-FILE TO-FILE

   In the simplest case, `diff' compares the contents of the two files
FROM-FILE and TO-FILE.  A file name of `-' stands for text read from
the standard input.  As a special case, `diff - -' compares a copy of
standard input to itself.

   If FROM-FILE is a directory and TO-FILE is not, `diff' compares the
file in FROM-FILE whose file name is that of TO-FILE, and vice versa.
The non-directory file must not be `-'.

   If both FROM-FILE and TO-FILE are directories, `diff' compares
corresponding files in both directories, in alphabetical order; this
comparison is not recursive unless the `-r' or `--recursive' option is
given.  `diff' never compares the actual contents of a directory as if
it were a file.  The file that is fully specified may not be standard
input, because standard input is nameless and the notion of "file with
the same name" does not apply.

   `diff' options begin with `-', so normally FROM-FILE and TO-FILE may
not begin with `-'.  However, `--' as an argument by itself treats the
remaining arguments as file names even if they begin with `-'.

   An exit status of 0 means no differences were found, 1 means some
differences were found, and 2 means trouble.

diff Options

Summary of options to `diff'.