Why is gulp-sass not creating output

Question

I'm trying to get gulp to compile some sass, however I can't seem to get it to write out anything. I'm not seeing an error and using sass to compile myself is successful. Here is what my config looks like:

var sass = require('gulp-sass');
var baseOutputDir = '../publish/homepage';
var cssOutputDir = baseOutputDir + '/css';
gulp.task('sass', function () {
    gulp.src(['./css-lib/Bootstrap/3.3.1/assets/stylesheets/_bootstrap.scss'])
        .pipe(sass())
        .on('error', function (err) { console.log(err.message); })
        .pipe(gulp.dest(cssOutputDir));
})

The bootstrap is a clone of https://github.com/twbs/bootstrap-sass

Answer 1

I'm use to LESS and not Sass. A file with an underscore in front won't generate a css file.