Git mergetool with three tabs

Question

I would like to configure a git mergetool setting with vanilla Vim 8.2 to open up three tabs:

• Tab A: The merged file (the file that is supposed to be edited)
• Tab B: Diff between base and local file
• Tab C: Diff between base and remote file

Now, I am trying to achieve this from the command line, but the moment Vim opens a new tab it will not open up a new file in the new tab. It almost looks like the tabs feature does not work well with command line arguments:

[mergetool "vimdifftabs"]
  cmd = vim -f -c "e $MERGED" -c "tabe $BASE" -c "diffs $LOCAL" -c "tabe $BASE" -c "diffs $REMOTE"

Looks like even this does not work:

[mergetool "vimdifftabs"]
  cmd = vim -f -c "e $MERGED" -c "tabe $BASE"

The second tab is empty, no file opened there. When I try to explicitly create the tab first and then edit the file:

[mergetool "vimdifftabs"]
  cmd = vim -f -c "e $MERGED" -c tabnew -c "e $BASE"

Vim says: No filename. But I tested that git is passing the base filename correctly in that variable. I am not getting it.

Answer 1

Found it, I had to escape quotes in the gitconfig! Here is the solution:

[mergetool "vimdifftabs"]
  cmd = vim -f -c \"tabe $BASE\" -c \"diffsplit $LOCAL\" -c \"tabe $BASE\" -c \"diffsplit $REMOTE\" \"$MERGED\"

Here is a slightly advanced version which highlights conflicts and goes to the top of the first (tab) file:

[mergetool "vimdifftabs"]
  cmd = vim -f -c \"tabe $BASE\" -c \"diffsplit $LOCAL\" -c \"tabe $BASE\" -c \"diffsplit $REMOTE\" -c tabfirst -c \"/=======\" -c \"normal gg\" \"$MERGED\"

Thanks