Kdiff3 won't open with mergetool command

Question

I have conflicts, so I type:

git mergetool

I then get a message saying:

Hit return to start merge resolution tool

Answer 1

Git has --auto hard coded as a command-line option to KDiff3, which causes the GUI not to show up if all conflicts are auto-resolvable by KDiff3.

We can change this default behavior by setting:

git config --global mergetool.kdiff3NoAuto.cmd "/c/Program Files/KDiff3/kdiff3.exe --L1 \"\$MERGED (Base)\" --L2 \"\$MERGED (Local)\" --L3 \"\$MERGED (Remote)\" -o \"\$MERGED\" \"\$BASE\" \"\$LOCAL\" \"\$REMOTE\""

which result in the ~/.gitconfig file (or you can directly modify the file):

[merge]
        tool = kdiff3
[mergetool "kdiff3"]
        path = C:/Program Files/KDiff3/kdiff3.exe
        trustExitCode = false
        cmd = \"/c/Program Files/KDiff3/kdiff3.exe\" --L1 \"$MERGED (Base)\" --L2 \"$MERGED (Local)\" --L3 \"$MERGED (Remote)\" -o \"$MERGED\" \"$BASE\" \"$LOCAL\" \"$REMOTE\"
[diff]
        guitool = kdiff3
[difftool "kdiff3"]
        path = C:/Program Files/KDiff3/kdiff3.exe
        trustExitCode = false

In this way, the kdiff3 will alway open whether there is still unsolved conflicts left.

Ref: https://stackoverflow.com/a/15813064/2303761