NAME
    interdiff - show differences between two diff files

SYNOPSIS
    interdiff [-p n] [-U n] [-d PAT] [-Bbiqwz]
   [--interpolate | --combine] [--no-revert-omitted]
   diff1 diff2

    interdiff {--help | --version}

DESCRIPTION
    interdiff creates a unified format diff that expresses the difference
    between two diffs. The diffs must both be relative to the same files.
    For best results, the diffs must have at least three lines of context.

    To reverse a patch, use /dev/null for diff2.

    To reduce the amount of context in a patch, use:

    interdiff -U1 /dev/null patchfile

    Since interdiff doesn't have the advantage of being able to look at the
    files that are  to be  modified, it has stricter requirements on the
    input format than patch(1) does. The output of GNU diff will be  okay,
    even with extensions, but if you intend to use a hand-edited patch it
    might be wise to clean up the offsets and counts  using recountdiff(1)
    first.

    The diffs may be in context format. The output, however, will be in
    unified format.

OPTIONS
    -h   Ignored, for compatibility with older versions of interdiff.
    This option will go away soon.

    -p n  When comparing filenames, ignore the first n pathname components
    from both patches. (This is similar to the -p option to GNU
    patch(1).)

    -q   Quieter output. Don't emit rationale lines at the beginning of
    each patch.

    -U n  Attempt to display n lines of context (requires at least n lines
    of context in both input files). (This is similar to the -U
    option to GNU diff(1).)

    -d pattern
    Don't display any context on files that match the shell wildcard
    pattern. This option can be given multiple times.

    Note that the interpretation of the shell wildcard pattern does
    not count slash characters or periods as special (in  other
    words, no flags are given to fnmatch). This is so that ``*/base-
    name''-type patterns can be given without limiting the number of
    pathname components.

    -i   Consider upper- and lower-case to be the same.

    -w   Ignore whitespace changes in patches.

    -b   Ignore changes in the amount of whitespace.

    -B   Ignore changes whose lines are all blank.

    -z   Decompress files with extensions .gz and .bz2.

    --interpolate
    Run as ``interdiff''. This is the default.

    --combine
    Run as ``combinediff''. See combinediff(1) for more information
    about how the behaviour is altered in this mode.

    --no-revert-omitted
    (For interpolation mode only) When a file is changed by the
    first patch but not by the second, don't revert that change.

    --help Display a short usage message.

    --version
    Display the version number of interdiff.

EXAMPLES
    Basic usage:

    interdiff -z 3.2pre1.patch.gz 3.2pre2.patch.gz

    Reversing a patch:

    interdiff patch /dev/null

    Reversing part of a patch (and ignoring the rest):

    filterdiff -i file.c patchfile | \
  interdiff /dev/stdin /dev/null

BUGS
    There are currently no known  bugs in interdiff; but there are some
    caveats. If you find a bug, please report it (along with a minimal test
    case) to Tim Waugh <twaugh@redhat.com>.

    There are some sets of patches in which there is just not enough infor-
    mation to produce a proper interdiff. In this case,  the strategy
    employed is to revert the original patch and apply the new patch. This,
    unfortunately, means that interdiffs are not guaranteed  to  be
    reversible.

SEE ALSO
   combinediff(1)

AUTHOR
    Tim Waugh <twaugh@redhat.com>.
    Man page edited by Michael K. Johnson <johnsonm@redhat.com>.