ydiff

Ydiff

.. image:: https://github.com/ymattw/ydiff/actions/workflows/test.yml/badge.svg :alt: Tests status :target: https://github.com/ymattw/ydiff/actions

Ydiff is a terminal-based tool to view colored, incremental diffs in a version-controlled workspace or from stdin, in side-by-side (similar to diff -y) or unified mode, and auto-paged. It only requires Python >= 3.3 without external dependencies and less as a pager.

The diffs in side-by-side mode appear below. See also the screenshots_ of the unified mode.

.. _screenshots: https://github.com/ymattw/ydiff/tree/26857b8/img

Theme "default" on a dark terminal background:

.. image:: https://raw.githubusercontent.com/ymattw/ydiff/26857b8/img/darkbg-side-by-side-default.png :alt: side by side, theme 'default' on a dark background :align: center :height: 300 px

Theme "default" on a light terminal background:

.. image:: https://raw.githubusercontent.com/ymattw/ydiff/26857b8/img/lightbg-side-by-side-default.png :alt: side by side, theme 'default' on a light background :align: center :height: 300 px

Theme "dark" on a dark terminal background:

.. image:: https://raw.githubusercontent.com/ymattw/ydiff/26857b8/img/darkbg-side-by-side-dark.png :alt: side by side, theme 'dark' on a dark background :align: center :height: 300 px

Theme "light" on a light terminal background:

.. image:: https://raw.githubusercontent.com/ymattw/ydiff/26857b8/img/lightbg-side-by-side-light.png :alt: side by side, theme 'light' on a light background :align: center :height: 300 px

Installation

Ydiff only depends on Python built-in libraries, so you can just download the source and run without worrying about any installation. Git tagged_ revisions will be packaged and uploaded to PyPI_ timely, however, packages hosted elsewhere are not (please note they are not managed by the author @ymattw_).

.. _tagged: https://github.com/ymattw/ydiff/tags .. _PyPI: http://pypi.python.org/pypi/ydiff .. _@ymattw: https://github.com/ymattw

To run from source directly, just save ydiff.py_ as ydiff to whatever directory which is in your $PATH, for example, $HOME/bin:

.. _ydiff.py: https://raw.github.com/ymattw/ydiff/master/ydiff.py

.. code-block:: bash

curl -L https://raw.github.com/ymattw/ydiff/master/ydiff.py > ~/bin/ydiff
chmod +x ~/bin/ydiff

To install from PyPI_:

.. code-block:: bash

pip install --upgrade ydiff

To install with Homebrew (Formula_) on macOS:

.. _Formula: https://github.com/Homebrew/homebrew-core/blob/master/Formula/y/ydiff.rb

.. code-block:: bash

brew install ydiff

To install on Fedora:

.. code-block:: bash

dnf install ydiff

To install on FreeBSD:

.. code-block:: bash

pkg install ydiff

Usage

Type ydiff -h to show usage::

$ ydiff -h
Usage: ydiff [options] [file|dir ...]

View colored, incremental diff in a workspace or from stdin, with side by side
and auto pager support.

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -s, --side-by-side    enable side-by-side mode (default True; DEPRECATED)
  -u, --unified         show diff in unified mode (disables side-by-side mode)
  -w N, --width=N       set text width for side-by-side mode, 0 (default) for
                        auto detection and fallback to 80 when not possible
  -l, --log             show log with changes from revision control
  -c WHEN, --color=WHEN
                        colorize mode 'auto' (default), 'always', or 'never'
  -t N, --tab-width=N   convert tab chars to this many spaces (default: 8)
  --wrap                wrap long lines in side-by-side mode (default True;
                        DEPRECATED)
  --nowrap, --no-wrap   do not wrap long lines in side-by-side mode
  -p PAGER, --pager=PAGER
                        pager application to feed output to, default is 'less'
  -o OPT, --pager-options=OPT
                        options to supply to pager application
  --theme=THEME         option to pick a color theme (one of dark, default,
                        light)

  Note:
    Option parser will stop on first unknown option and pass them down to
    underneath revision control. Environment variable YDIFF_OPTIONS may be
    used to specify default options that will be placed at the beginning
    of the argument list.

Read diff from local modification in a Git/Mercurial/Perforce/Svn workspace (output from e.g. git diff, svn diff):

.. code-block:: bash

cd proj-workspace
ydiff                       # view colored side by side diff, auto set text
                            # width based on terminal size
ydiff -u                    # view colored incremental diff in unified mode
ydiff -w 90                 # use text width 90, wrap long lines
ydiff --no-wrap             # auto set text width but do not wrap long lines
ydiff file1 dir2            # view modification of given files/dirs only
ydiff -w90 -U10             # pass '-U10' to underneath revision diff tool
ydiff --cached              # show git staged diff (git diff --cached)
ydiff -r1234                # show svn diff to revision 1234

Read log with changes in a Git/Mercurial/Svn workspace (output from e.g. git log -p, svn log --diff), note --diff option is new in svn 1.7.0:

.. code-block:: bash

cd proj-workspace
ydiff -l                    # read log along with changes, side by side
ydiff -lu                   # equivalent to ydiff -l -u, unified mode
ydiff -l -w90 --no-wrap     # set text width 90 and disable wrapping
ydiff -l file1 dir2         # see log with changes of given files/dirs only

Utilize a specific pager application:

.. code-block:: bash

ydiff -p more                   # use "more" as a pager
ydiff -p cat                    # when neither less nor more is avilable
ydiff -o "-FRSX --shift 2"      # customized option (pager defaults to less)

Pipe in a diff:

.. code-block:: bash

git log -p -2 | ydiff       # view git log with changes of last 2 commits
git show 15bfa | ydiff      # view a given git commit, side by side
svn diff -r1234 | ydiff     # view svn diff comparing to given revision
diff -u file1 file2 | ydiff # view diff between two files (note the '-u')
diff -ur dir1 dir2 | ydiff  # view diff between two dirs

# View diff in a GitHub pull request, side by side
curl https://github.com/ymattw/ydiff/pull/11.diff | ydiff

# View a patch file in colored unified format.
ydiff -u < foo.patch

Redirect output to another patch file is safe even without -u:

.. code-block:: bash

svn diff -r PREV | ydiff > my.patch

Customized themes

You can define your own themes in ~/.config/ydiff/themes.ini. Check out the built-in themes_ for examples.

.. _built-in themes: https://github.com/search?q=repo%3Aymattw%2Fydiff+%2F_BUILTIN_THEMES+%3D%2F&type=code

The section names are theme names. Undeclared theme keys will inherit values from the same-named built-in theme or from the "default" theme otherwise.

Notes

• Ydiff only supports diffs in Unified Format_. Diffs in other format may be converted to Unified Format via tool filterdiff (usually offered by package patchutils.)

  .. _Unified Format: https://en.wikipedia.org/wiki/Diff#Unified_format

• Environment variable YDIFF_OPTIONS may be used to specify default options that will be placed at the beginning of the argument list, for example:

  .. code-block:: bash

  export YDIFF_OPTIONS='-w100' ydiff foo # equivalent to "ydiff -w100 foo"

• If you feel more comfortable with a command such as git d to trigger the ydiff command, you may symlink the executable to one named git-d, or configure an alias:

  .. code-block:: bash

  Create a symlink git-d -> ydiff

  D=$(dirname $(which ydiff)); ln -s ydiff $D/git-d

  Or configure an alias

  git config --global alias.d '!ydiff'

Known issues

• Wide characters may cause alignment problem in side-by-side mode.
• Terminal might be in a mess on exception (type reset can fix it).

.. vim:set ft=rst et sw=4 sts=4 tw=79:

Change log

Version 1.5 (2025-12-06)

- Support customized themes in INI format
- Only read stdin when redirected from a regular file or pipe
- Apply --color=never option to git diff and git log
- Release both source and wheel packages

Version 1.4.2 (2024-11-18)

- Compatibility Fix: Ensure ydiff works properly with Python 3.3 and later.

Version 1.4.1 (2024-11-13)

• Fix setup() dependency: MANIFEST.in is still required for Python < 3.8 to pack data files

Version 1.4 (2024-11-13) Revoked due to #123

• Fine-grained, word-level diff for change blocks
• New --theme option for selecting different themes
• Options --side-by-side, --width 0, and --wrap become default (use --unified/--nowrap for legacy behavior)
• Python 2, 3.1, 3.2 support is officially dropped

Version 1.3 (2024-04-02)

• Dropped context diff support
• Handle East Asian wide characters (thanks to @roy2220)
• Fix SIGPIPE issue on Windows (unofficial support, thanks to @kingsamchen)
• Bump Python requirement to >=2.6 (Python 2 support is no longer tested)

Version 1.2 (2020-08-08)

• Support perforce workspaces
• Support pager customization via --pager and --pager_options
• Support running on Windows (requires less which is offered by git-bash)
• Fix a bug where reading stdin does not work outside a CVS workspace
• Fix tab expansion, expands to the next stop modulo tab width
• Performance improvement

Version 1.1 (2018-06-05)

• Rename from cdiff to ydiff to avoid binary name conflict on major distributions, CDIFF_OPTIONS still works but will be deprepated soon
• New option --wrap to wrap long lines in side-by-side view

Version 1.0 (2016-12-31)

• Use environment variable CDIFF_OPTIONS to hold default options

Version 0.9.8 (2016-01-16)

• More robust parser to tolerate evil unified diff

Version 0.9.7 (2015-04-24)

• Fix unexpected side-by-side output for diff of diff
• Better color to work with solarized color scheme

Version 0.9.6 (2014-06-20)

• Fix TypeError exception in auto width logic

Version 0.9.5 (2014-06-19)

• Option --width 0 now fits terminal size automatically
• Enable smooth horizontal scrolling with less option --shift 1

Version 0.9.4 (2014-06-04)

• Respect the LESS environment variable
• Support python 3.4
• Fix curl options in document

Version 0.9.3 (2013-09-28)

• Moved screenshots to 'gh-pages' branch
• Handle all keyboard interrupts more completely
• Explicitly set default encoding to utf-8
• Fixed broken output diff when I/O with filterdiff in nonblocking mode

Version 0.9.2 (2013-06-21)

• Enahanced option parser now pass unknown option to underneath revision control, user can use cdiff --cached, cdiff -U5 directly

Version 0.9.1 (2013-05-20)

• Use --no-ext-diff to disable GIT_EXTERNAL_DIFF and diff.external which might break cdiff output

Version 0.9 (2013-03-23)

• Supports reading context diff via filterdiff (patchutils)
• Fixed a diff parser bug which misread git commit message as common line
• Lots of code refactor

Version 0.8 (2013-03-13)

• Parser is now robust enough to handle dangling headers and short patch
• PEP8 (with minor own flavors) and other code lint
• Change 'Development Status' to stable

Version 0.7.1 (2013-02-25)

• Handle 'Binary files ... differ'
• Document update for known issues

Version 0.7 (2013-02-23)

• Support reading diff or log for given files/dirs in workspace
• Support diff generated from diff -ru dir1 dir2
• Usage change: reading a patch and comparing two files need stdin redirect

Version 0.6 (2013-02-20)

• A few performance tuning and code clean up
• Add unit test cases with coverage 70%
• Show merge history in svn log

Version 0.5.1 (2013-02-19)

• Fixed incorrect yield on diff missing eof
• Fixed a bug in diff format probe
• Handle keyboard interrupt and large diffs in non-color mode
• Code clean up

Version 0.5 (2013-02-18)

• Support read output from svn diff --log and hg log -p
• Streamline reading large patch set
• New --log (-l) option to read revision control diff log (thanks to Steven Myint_)

Version 0.4 (2013-02-16)

• New option -c WHEN (--color WHEN) to support auto test
• Auto regression test now on Travis

Version 0.3 (2013-02-07)

• Support compare two files (wrapper of diff)

Version 0.2 (2013-02-06)

• Move cdiff.py to top dir for better meta info management

Version 0.1 (2013-02-05)

• New --version option
• setup.py now read version from source code

Version 0.0.4 (2013-02-04)

• Add CHANGES for history track and better versioning

Version 0.0.3 (2013-02-04)

• Publish on PyPI, supports read patch from file, pipe and diff output from revision tools (thanks to Steven Myint_)

.. _Steven Myint: https://github.com/myint

.. vim:set ft=rst et sw=4 sts=4 tw=79: