INTERDIFF(1)

NAME
interdiff - show differences between two unified 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 diff that expresses the difference between two unified diffs (patches created with the -u option to diff). 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.

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 ``*/basename''-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>.

The -U option is a bit erratic: it can control the amount of context displayed for files that are modified in both patches, but not for files that only appear in one patch (which appear with the same amount of context in the output as in the input). If you really want this changed, let me know.

There are some sets of patches in which there is just not enough information 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>.