[git] Git Diff with Beyond Compare

I have succeeded in getting git to start Beyond Compare 3 as a diff tool however, when I do a diff, the file I am comparing against is not being loaded. Only the latest version of the file is loaded and nothing else, so there is nothing in the right pane of Beyond Compare.

I am running git 1.6.3.1 with Cygwin with Beyond Compare 3. I have set up beyond compare as they suggest in the support part of their website with a script like such:

#!/bin/sh  
# diff is called by git with 7 parameters:  
# path old-file old-hex old-mode new-file new-hex new-mode  
"path_to_bc3_executable" "$2" "$5" | cat

Has anyone else encountered this problem and know a solution to this?

Edit:
I have followed the suggestions by VonC but I am still having exactly the same problem as before. I am kinda new to Git so perhaps I am not using the diff correctly.

For example, I am trying to see the diff on a file with a command like such:
git diff main.css

Beyond Compare will then open and only display my current main.css in the left pane, there is nothing in the right pane. I would like the see my current main.css in the left pane compared to the HEAD, basically what I have last committed.

My git-diff-wrapper.sh looks like this:

#!/bin/sh  
# diff is called by git with 7 parameters:  
# path old-file old-hex old-mode new-file new-hex new-mode  
"c:/Program Files/Beyond Compare 3/BCompare.exe" "$2" "$5" | cat

My git config looks like this for Diff:

[diff]  
external = c:/cygwin/bin/git-diff-wrapper.sh

Run these commands for Beyond Compare 2:

git config --global diff.tool bc2
git config --global difftool.bc2.cmd "\"c:/program files (x86)/beyond compare 2/bc2.exe\" \"$LOCAL\" \"$REMOTE\""
git config --global difftool.prompt false

Run these commands for Beyond Compare 3:

git config --global diff.tool bc3
git config --global difftool.bc3.cmd "\"c:/program files (x86)/beyond compare 3/bcomp.exe\" \"$LOCAL\" \"$REMOTE\""
git config --global difftool.prompt false

Then use git difftool

Update for BC4 64bit: This works for Git for Windows v.2.16.2 and Beyond Compare 4 - v.4.2.4 (64bit Edition)

I manually edited the .gitconfig file located in my user root "C:\Users\MyUserName" and replaced the diff/difftool and merge/mergetool tags with

[diff]
  tool = bc
[difftool "bc"]
  path = 'C:/Program Files/Beyond Compare 4/BComp.exe'
[difftool "bc"]
  cmd = \"C:/Program Files/Beyond Compare 4/BComp.exe\" \"$LOCAL\" \"$REMOTE\"
[difftool]
  prompt = false
[merge]
  tool = bc
[mergetool "bc"]
  path = 'C:/Program Files/Beyond Compare 4/BComp.exe'
[mergetool "bc"]
  cmd = \"C:/Program Files/Beyond Compare 4/BComp.exe\" \"$REMOTE\" \"$LOCAL\" \"$BASE\" \"$MERGED\"

For whatever reason, for me, the tmp file created by git diff was being deleted before it opened in beyond compare. I had to copy it out to another location first.

cp -r $2 "/cygdrive/c/temp$2"
cygstart /cygdrive/c/Program\ Files\ \(x86\)/Beyond\ Compare\ 3/BCompare.exe "C:/temp$2" "$5"

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.

For MAC after doing lot of research it worked for me..! 1. Install the beyond compare and this will be installed in below location

/Applications/Beyond\ Compare.app/Contents/MacOS/bcomp

Please follow these steps to make bc as diff/merge tool in git http://www.scootersoftware.com/support.php?zz=kb_mac

Thanks to @dahlbyk, the author of Posh-Git, for posting his config as a gist. It helped me resolve my configuration issue.

[diff]
    tool = bc3
[difftool]
    prompt = false
[difftool "bc3"]
    cmd = \"c:/program files (x86)/beyond compare 3/bcomp.exe\" \"$LOCAL\" \"$REMOTE\"
[merge]
    tool = bc3
[mergetool]
    prompt = false
    keepBackup = false
[mergetool "bc3"]
    cmd = \"c:/program files (x86)/beyond compare 3/bcomp.exe\" \"$LOCAL\" \"$REMOTE\" \"$BASE\" \"$MERGED\"
    trustExitCode = true
[alias]
    dt = difftool
    mt = mergetool

The difference is in the exe being called: set it up to call bcomp.exe and it'll work fine. Configure your environment to call bcompare.exe and you'll end up with the side of the comparison taken from your revision system being empty.

For git version 2.15.1.windows.2 with BC2.exe.

The config below finally works on my machine.

[difftool "bc2"] cmd = \"c:/program files/beyond compare 2/bc2.exe\" ${LOCAL} ${REMOTE}

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.

Official documentation worked for me

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.

Please notice you make a wrong path of $2. because you are under Cygwin but BC3 not, so you should specify a full path for it. such as "d:/cygwin$2"

Please refer my git-diff-wrapper.sh here:

$ cat ~/git-diff-wrapper.sh
#!/bin/sh
echo $2
echo $5
/cygdrive/c/Program\ Files\ \(x86\)/Beyond\ Compare\ 3/BCompare.exe "d:/programs/cygwin$2" "$5"

Good luck.

Run these commands for Beyond Compare 3(if the BCompare.exe path is different in your system, please replace it according to yours):

git config --global diff.tool bc3
git config --global difftool.bc3.cmd "\"c:/program files (x86)/beyond compare 3/BCompare.exe\" \"$LOCAL\" \"$REMOTE\""
git config --global difftool.prompt false

Then use git difftool

http://rubenlaguna.com/wp/2010/08/05/visual-difftool-cygwin-git/ has a solution that I adopted to work for BeyondCompare: http://gist.github.com/564573

Here is my config file. It took some wrestling but now it is working. I am using windows server, msysgit and beyond compare 3 (apparently an x86 version). Youll notice that I dont need to specify any arguments, and I use "path" instead of "cmd".

[user]
        name = PeteW
        email = [email protected]
[diff]
        tool = bc3
[difftool]
        prompt = false
[difftool "bc3"]
        path = /c/Program Files (x86)/Beyond Compare 3/BComp.exe
[merge]
        tool = bc3
[mergetool]
        prompt = false
        keepBackup = false
[mergetool "bc3"]
        path = /c/Program Files (x86)/Beyond Compare 3/BComp.exe
        trustExitCode = true
[alias]
        dt = difftool
        mt = mergetool

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