Then you can simply type "java ..." to run Java applications via the command line. Second of all, BuildTools.jar is the JAR necessary to compile the latest version of Spigot. That is NOT a Minecraft server. When you run "java -jar BuildTools.jar", that will generate a "spigot.jar" file in the directory where the BuildTools JAR is (along with a bunch of materials needed to build the artifact).
Are you trying to build a new version of Spigot? Or are you trying to start a Spigot server?