title: How to execute runMain from custom task?
body: <p>I'm using sbt v0.13.5</p>
  
  <p>In my project, I'd like to have an sbt task that can accept some input (a single string), do some work on it and spit back some output (again, a single string). I've created a helper class in my project that does this that I can call from the terminal via <code>sbt runMain</code> (<code>sbt "runMain com.example.utils.ClassName someArgument"</code>).</p>
  
  <p>What I'd like is to save myself some typing and have an sbt task that does this. I'd like to just be able to type <code>sbt doThing withStuff</code> and have a taskKey named <code>doThing</code> that calls <code>runMain</code> with the name of the class to run and whatever argument was passed in.</p>
  
  <p>I know how to create tasks but I can't seem to figure out how to call <code>runMain</code> from a custom task definition in my build.sbt. Can anyone point me in the correct direction?</p>