`mergetool.kdiff3.path`. Otherwise, 'git-mergetool' assumes the
tool is available in PATH.
+
-Instead of running one of the known merge tool programs
+Instead of running one of the known merge tool programs,
'git-mergetool' can be customized to run an alternative program
-by specifying the command line to invoke in a configration
+by specifying the command line to invoke in a configuration
variable `mergetool.<tool>.cmd`.
+
When 'git-mergetool' is invoked with this tool (either through the
merge resolution.
+
If the custom merge tool correctly indicates the success of a
-merge resolution with its exit code then the configuration
+merge resolution with its exit code, then the configuration
variable `mergetool.<tool>.trustExitCode` can be set to `true`.
Otherwise, 'git-mergetool' will prompt the user to indicate the
success of the resolution after the custom tool has exited.