The following code will setup the task that will generate an error report whenever an problem is detected in one of the specified script files:

gulpfile.js

"use strict";
var gulp = require('gulp');
var gutil = require('gulp-util');
var stylish = require('jshint-stylish');
var jshint = require('gulp-jshint');

gulp.task('lint', function() {

    // this will exclude the modules folder
    var sourcefiles = [
        './**/*.js',
        '!./node_modules/**',
        '!gulpfile.js'
        ];

    gulp.src( sourcefiles )
        .pipe(jshint( '.jshintrc' ))
        // .pipe(jshint.reporter('default'));
        .pipe( jshint.reporter(stylish) );
});

gulp.task('watch', function(){

    // adds a watch that executes the lint task everytime
    // a file is modified 
    gulp.watch( ['.jshintrc', '*.js', 'lib/*.js'], ['lint'] );
});

// define the default task that is invoked 
// when "gulp" is executed on the cmd-line
gulp.task('default', [ 'watch' ]);