Documentation/config/difftool.txt

diff.tool::
	Controls which diff tool is used by linkgit:git-difftool[1].
	This variable overrides the value configured in `merge.tool`.
	The list below shows the valid built-in values.
	Any other value is treated as a custom diff tool and requires
	that a corresponding difftool.<tool>.cmd variable is defined.

diff.guitool::
	Controls which diff tool is used by linkgit:git-difftool[1] when
	the -g/--gui flag is specified. This variable overrides the value
	configured in `merge.guitool`. The list below shows the valid
	built-in values. Any other value is treated as a custom diff tool
	and requires that a corresponding difftool.<guitool>.cmd variable
	is defined.

difftool.<tool>.cmd::
	Specify the command to invoke the specified diff tool.
	The specified command is evaluated in shell with the following
	variables available:  'LOCAL' is set to the name of the temporary
	file containing the contents of the diff pre-image and 'REMOTE'
	is set to the name of the temporary file containing the contents
	of the diff post-image.
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See the `--tool=<tool>` option in linkgit:git-difftool[1] for more details.

difftool.<tool>.path::
	Override the path for the given tool.  This is useful in case
	your tool is not in the PATH.

difftool.trustExitCode::
	Exit difftool if the invoked diff tool returns a non-zero exit status.
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See the `--trust-exit-code` option in linkgit:git-difftool[1] for more details.

difftool.prompt::
	Prompt before each invocation of the diff tool.

difftool.guiDefault::
	Set `true` to use the `diff.guitool` by default (equivalent to specifying
	the `--gui` argument), or `auto` to select `diff.guitool` or `diff.tool`
	depending on the presence of a `DISPLAY` environment variable value. The
	default is `false`, where the `--gui` argument must be provided
	explicitly for the `diff.guitool` to be used.