Git Diff with Beyond Compare

The Beyond Compare support page is a bit brief.

Check my diff.external answer for more (regarding the exact syntax)

Extract:

$ git config --global diff.external <path_to_wrapper_script>

at the command prompt, replacing with the path to "git-diff-wrapper.sh", so your ~/.gitconfig contains

-->8-(snip)--
[diff]
    external = <path_to_wrapper_script>
--8<-(snap)--

Be sure to use the correct syntax to specify the paths to the wrapper script and diff tool, i.e. use forward slashed instead of backslashes. In my case, I have

[diff]
    external = c:/Documents and Settings/sschuber/git-diff-wrapper.sh

in .gitconfig and

"d:/Program Files/Beyond Compare 3/BCompare.exe" "$2" "$5" | cat

in the wrapper script.

Note: you can also use git difftool.

With later versions of Git and Beyond Compare than what OP had, the below is what worked for me:

• Git for Windows - v.2.22.0
• Beyond Compare 4 - v.4.2.10 (64-bit Edition)

Config file to be edited: %USERPROFILE%\.gitconfig

Replace the diff/difftool and merge/mergetool tags with

[diff]
    tool = bc4
[difftool]
    prompt = false
[difftool "bc4"]
    cmd = \"c:/program files/beyond compare 4/bcomp.exe\" "$LOCAL" "$REMOTE"
[merge]
    tool = bc4
[mergetool]
    prompt = false
[mergetool "bc4"]
    trustExitCode = true
    cmd = \"c:/program files/beyond compare 4/bcomp.exe\" "$LOCAL" "$REMOTE" "$BASE" "$MERGED"

it looks like BC3 only supports 3 way merge for PRO Edition. http://www.scootersoftware.com/moreinfo.php?zz=kb_editions

To use beyond compare in MAC OSX you need to do the following: Install beyond compare command-line tools from the menu:

Then you need to run those commands:

git config --global diff.tool bc3

git config --global merge.tool bc3
git config --global mergetool.bc3.trustExitCode true

After that, you could run git mergetool in the folder with git conflict and BC will work as expected

If you are running windows 7 (professional) and Git for Windows (v 2.15 or above), you can simply run below command to find out what are different diff tools supported by your Git for Windows

git difftool --tool-help

You will see output similar to this

git difftool --tool=' may be set to one of the following:
vimdiff vimdiff2 vimdiff3

it means that your git does not support(can not find) beyond compare as difftool right now.

In order for Git to find beyond compare as valid difftool, you should have Beyond Compare installation directory in your system path environment variable. You can check this by running bcompare from shell(cmd, git bash or powershell. I am using Git Bash). If Beyond Compare does not launch, add its installation directory (in my case, C:\Program Files\Beyond Compare 4) to your system path variable. After this, restart your shell. Git will show Beyond Compare as possible difftool option. You can use any of below commands to launch beyond compare as difftool (for example, to compare any local file with some other branch)

git difftool -t bc branchnametocomparewith -- path-to-file
or 
git difftool --tool=bc branchnametocomparewith -- path-to-file

You can configure beyond compare as default difftool using below commands

   git config --global diff.tool bc

p.s. keep in mind that bc in above command can be bc3 or bc based upon what Git was able to find from your path system variable.

Windows 10, Git v2.13.2

My .gitconfig. Remember to add escape character for '\' and '"'.

[diff]
    tool = bc4
[difftool]
    prompt = false
[difftool "bc4"]
    cmd = \"C:\\Program Files\\Beyond Compare 4\\BCompare.exe\" \"$LOCAL\" \"$REMOTE\"
[merge]
    tool = bc4
[mergetool "bc4"]
    path = C:\\Program Files\\Beyond Compare 4\\BCompare.exe

You may reference setting up beyond compare as difftool for using git commands to config it.

Worked for me on Windows 10

Run in git terminal,

git config --global diff.tool bc3
git config --global difftool.bc3.path "c:/program files/beyond compare 4/bcomp.exe"
git config --global merge.tool bc3
git config --global mergetool.bc3.path "c:/program files/beyond compare 4/bcomp.exe"