How to use gulp in laravel on ubuntu 16.04

I have problem with gulp in my project. I installed node, npm, gulp and I created file gulpfile.js.

If I use command gulp never nothing happens.

I don't know what is incorrect.

Please help me.

My code for example:

var gulp = require('gulp'),
    watch = require('gulp-watch'),
    sass = require('gulp-sass'),
    css_ = require('gulp-minify-css'),
    concat = require('gulp-concat'),
    livereload = require('gulp-livereload'),
    lr = require('tiny-lr'),
    clean = require('gulp-clean'),
    less = require('gulp-less'),
    server = lr();


var paths_css = {

    css: [  '/bower_components/AdminLTE/bootstrap/css/bootstrap.min.css',
            '/bower_components/AdminLTE/dist/css/AdminLTE.min.css',
            '/bower_components/AdminLTE/plugins/iCheck/flat/blue.css',
            '/bower_components/AdminLTE/plugins/morris/morris.css',
            '/bower_components/AdminLTE/plugins/jvectormap/jquery-jvectormap-1.2.2.css']
};


gulp.task('css', function() {
   return gulp.src(paths_css.css)
        .pipe(concat('css.css'))
        .pipe(sass())
        .pipe(gulp.dest('public/css/'));
});


gulp.task('default', ['css']);

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