ernal commands with params too, example:
		KUBECTL_EXTERNAL_DIFF="colordiff -N -u"

		By default, the "diff" command available in your path will be
		run with the "-u" (unified diff) and "-N" (treat absent files as empty) options.

		Exit status:
		 0
		No differences were found.
		 1
		Differences were found.
		 >1
		Kubectl or diff failed with an error.

		Note: KUBECTL_EXTERNAL_DIFF, if used, is expected to follow that convention.