Gulpfile recipe for gulp-less with gulp.watch

Gulpfile.js

var gulp = require('gulp');
var less = require('gulp-less');
var plumber = require('gulp-plumber');
var sourcemaps = require('gulp-sourcemaps');

var lesses = ['src/less/**/*.less'];
gulp.task('less', function () {
  return gulp.src(lesses)
    .pipe(sourcemaps.init())
    .pipe(plumber())
    .pipe(less({
      paths: [__dirname + '/node_modules/bootstrap/less']
    }))
    .on('error', function (err) {
      console.error(err.toString());
      this.emit('end');
    })
    .pipe(sourcemaps.write('.', {sourceRoot: '.'}))
    .pipe(gulp.dest('public/css'));
});

gulp.task('watch', function () {
  gulp.watch(lesses, function () {
    gulp.start(['less']);
  });
});