Question

I’ve just started using Git and it’s possible I’ve missed something obvious, but here goes:

• I’m using msysgit 1.6.2.2 on Windows XP
• While installing, I picked option 1 to “Use Git Bash only”

I’m trying to put together a wrapper script that I can use to replace the built in git diff with DiffMerge. Based on this thread on SO, I created the following batch file:

@echo off
REM ---- Switch forward slashes to back slashes ----
set oldW=%2
set oldW=%oldW:/=\%
set newW=%5
set newW=%newW:/=\%

REM ---- Launch DiffMerge ----
"C:/Programs/SourceGear/DiffMerge/DiffMerge.exe" /title1="Old Version" %oldW% /title2="New Version" %newW%

I placed the bat file under %GIT_INSTALL%/cmd and edited my .gitconfig file as follows:

[diff]
external = C:/Programs/git/cmd/git-diff-wrapper.bat

If i launch Git Bash and execute
git diff HEAD HEAD~ — myfile

I get a message File (\dev\null) not found – which given I’m on Windows is not surprising.

Pressing on, I launched gitk and under Edit>Preferences, I chose the same wrapper script. Trying the “external diff” option for a particular file gives the cryptic error message Unknown Option "

Clearly, I have no idea what I’m doing anymore so any help would be much appreciated.

Answer 1

I just experienced a somewhat similar experience with setting Notepad++ as my external editor with msysgit1.6.2.2.

The key was to realize the wrapper was not a DOS script, but a /bin/sh script.

So try to put in your “.bat” (even though it is not exactly a bat script, the extension is not important here):

#!/bin/sh

# diff is called by git with 7 parameters:
# path old-file old-hex old-mode new-file new-hex new-mode

"C:/Programs/SourceGear/DiffMerge/DiffMerge.exe" /title1="Old Version" "$2" /title2="New Version" "$5" | cat

Do not worry about making all the ‘\‘ go ‘/‘: it is done by the Git scripts calling the external diff tool.

I did not test it with DiffMerge, but with WinMerge, it works just fine, both from a DOS session or a Git Shell.

#!/bin/sh
"C:/Program Files/WinMerge/WinMergeU.exe" -e -ub "$2" "$5" | cat

(with the ‘-e‘ option, I have just ot type on ‘ESC‘ to close and quit the diff tool: that works great!)

---

average_geek adds in the comments:

added the ‘/bin/sh‘ header and tried running git diff again.
This time the error is:
Unexpected parameter 'C:/Docume~/avggeek/LOCALS~1/Temp/.diff_b08444
Is there a way to see what are the parameters getting passed when I call git diff ?

1/ There actually is a way to see what are the parameters getting passed!
Add the following line in the C:\Program Files\Git\libexec\git-core\git-sh-setup file:

git_editor() {
    : "${GIT_EDITOR:=$(git config core.editor)}"
    : "${GIT_EDITOR:=${VISUAL:-${EDITOR}}}"
    case "$GIT_EDITOR,$TERM" in
    ,dumb)
        echo >&2 "No editor specified in GIT_EDITOR, core.editor, VISUAL,"
        echo >&2 "or EDITOR. Tried to fall back to vi but terminal is dumb."
        echo >&2 "Please set one of these variables to an appropriate"
        echo >&2 "editor or run $0 with options that will not cause an"
        echo >&2 "editor to be invoked (e.g., -m or -F for git-commit)."
        exit 1
        ;;
    esac
#### ADD THIS LINE BELOW
    echo >&2 "editor is ${GIT_EDITOR:=vi} $@."
#### END ADDITION ABOVE
    eval "${GIT_EDITOR:=vi}" '"$@"'
}

You will see what editor is being called, with what parameter.

Now, regarding the “Unexpected parameter” part:
I did have the same kind of error when I called WinMergeU.exe with “/e /ub” instead of “-e -ub“, so first question is:
Are you sure that the “/title1” bit could not be used as “-title1” or “-t1” or “--title1” or “--t1” ? That is what Is can see from the chapter 9 “Command Lines Arguments” of the pdf documentation of DiffMerge.
If not, I suspect some double quotes are in order for delimiting properly the different parameters. Something like:

"/title1="Old Version"" "$2" "/title2="New Version"" "$5"
or
"/title1=\"Old Version\"" "$2" "/title2=\"New Version\"" "$5"

But my money would rather be on the “-title1” or “-t1” form:

-t1="Old Version" "$2" -t2="New Version" "$5"

should work just fine.