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Beyond Compare has been my favorite comparison tool for a while now. It is cross-platform and makes diffs and 3-way merges very easy to understand and visualize.

Configuring Beyond Compare 4

Git for Linux

To get it working on any linux flavor is pretty straight forward. Run these commands from terminal:

git config --global diff.tool bc
git config --global difftool.prompt false
git config --global difftool.bc trustExitCode true
git config --global merge.tool bc
git config --global mergetool.bc trustExitCode true

In order to get directory diffs working (e.g. git difftool --dir-diff), I had to tweak the settings a little bit. By default, git uses symlinks to do the directory diff and BC4 will not follow those by default yielding something that looks like this:

broken directory diff

There are a couple of ways to fix this (courtesy of StackOverflow). The approach I like is updating Beyond Compare to follow the symlinks.

In the Folder Compare, click the Rules toolbar button (referee icon). Go to the Handling tab. Check Follow symbolic links. To make this affect all new sessions, change the dropdown at the bottom of the dialog from Use for this view only to Also update session defaults before you click OK.

Git for Windows

On Windows, in addition to the above commands, you need to tell git the path to bcomp.exe:

git config --global difftool.bc.path "c:/program files/beyond compare 4/bcomp.exe"
git config --global mergetool.bc.path "c:/program files/beyond compare 4/bcomp.exe"

You don’t need to do anything special to get directory diffs working on Windows.

Git for Visual Studio

Visual Studio includes a builtin diff viewer that is pretty nice. However, I don’t find it as useful as I do Beyond Compare. Not to mention, it doesn’t support 3-way merge. Instead of using your global git config, it forces you to change the git config file in the repo. Specifically, you need to open git/config in the repo and add the following:

	tool = bc4
[difftool "bc4"]
	cmd = \"C:\\Program Files\\Beyond Compare 4\\BComp.exe\" \"$LOCAL\" \"$REMOTE\"
	tool = bc4
[mergetool "bc4"]
	cmd = \"C:\\Program Files\\Beyond Compare 4\\BComp.exe\" \"$REMOTE\" \"$LOCAL\" \"$BASE\" \"$MERGED\"

Now, among other things, you can right-click files in VS and choose Compare with Unmodified to open Beyond Compare.

Configuring Beyond Compare 3

Git for Linux

Pretty much the only difference from above is using bc3 instead of bc:

git config --global diff.tool bc3
git config --global difftool.prompt false
git config --global difftool.bc3 trustExitCode true
git config --global merge.tool bc3
git config --global mergetool.bc3 trustExitCode true

Git for Windows

On Windows, it is a little more work. In addition to the above, you need to tell git the path to bcomp.exe:

git config --global difftool.bc3.path "c:/program files (x86)/beyond compare 3/BCompare.exe"
git config --global mergetool.bc3.path "c:/program files (x86)/beyond compare 3/bcomp.exe"

The reason I am using BCompare.exe for the difftool instead of bcomp.exe is described here. When using the new --dir-diff option of the git difftool command:

git difftool 4e560^^ --dir-diff
#4e560 is your commit hash that you want to show a whole directory-diff on in BC

Beyond Compare 3 has a bug that is not fixed as of v3.3.12 where you need to employ this workaround. If you don’t do it, bcomp.exe will exit too early, and no files will be available to diff while you are viewing the directory diff.

This is fixed in BC4, so you should probably just upgrade to that.

Using It

Once you have it setup, you can easily run

git difftool path/to/my/file.js

in your working copy to show unstaged changes. If you want to see a diff of the whole directory, you can run:

git difftool --dir-diff

which opens BC’s directory comparison which can’t be beat IMO.

To resolve merge conflicts:

git mergetool

That will cycle through each merge conflict in the working copy and as long as you save the file from BC, the conflict will be marked resolved by git (hence the mergetool.bc trustExitCode setting).