javascript - gulp-ruby-sass Error: must provide pattern -

this directory structure:

i set workstation, , set gulp file work on folder format, not working properly.

this gulp file:

var gulp      = require('gulp'),     sass        = require('gulp-ruby-sass'),     imagemin    = require('gulp-imagemin'),     changed     = require('gulp-changed'),     browsersync = require('browser-sync'),     livereload = require('gulp-livereload'),         gp_concat = require('gulp-concat'),     gp_rename = require('gulp-rename'),     gp_uglify = require('gulp-uglify'),     watch = require('gulp-watch');   gulp.task('sass', function () {   gulp.src('./app/template/css/style_v1.scss')     .pipe(sass())     .on('error', function (err) { console.log(err.message); })     .pipe(gulp.dest('./dist/css'))     .pipe(livereload()); });  gulp.task('compress', function() {   gulp.src('./app/*.js')    .pipe(gp_concat('concat.js'))         .pipe(gulp.dest('dist'))         .pipe(gp_rename('script.min.js'))         .pipe(gp_uglify())         .pipe(gulp.dest('./dist/js')); });  gulp.task('jpg', function() {     gulp.src('./template/img/**/*.*')         .pipe(changed('./dist/img/'))         .pipe(imagemin({             progressive: true         }))         .pipe(gulp.dest('./dist/img/')); });  gulp.task('browser-sync', function() {     browsersync.init(['./dist/css/**', 'index.php'], {         server: {             basedir: './',             index: 'index.php'         }     }); });  gulp.task('watch', ['sass', 'browser-sync','compress'], function () {      return watch('./app/template/css/style_v1.scss', function () {         gulp.src('./app/template/css/style_v1.scss')             .pipe(gulp.dest('build'));     }); }); 

when run gulp watch returns this:

(node:6668) fs: re-evaluating native module sources not supported. if using graceful-fs module, please update more recent version. [08:42:23] using gulpfile /var/www/html/evandro/sistema_metas/gulpfile.js [08:42:23] starting 'sass'... [08:42:23] 'sass' errored after 7.09 ms [08:42:23] error: must provide pattern 

what problem?

i have code, css watch not work, watch html, can be?

gulp-ruby-sass works differently other gulp plugins. don't pass .pipe(). if take @ the documentation says following:

use gulp-ruby-sass instead of gulp.src compile sass files.

that means have use this:

var sass = require('gulp-ruby-sass');  gulp.task('sass', function () {   return sass('./app/template/css/style_v1.scss')     .on('error', function (err) { console.log(err.message); })     .pipe(gulp.dest('./dist/css'))     .pipe(livereload()); }); 

alternatively can use gulp-sass plugin instead of gulp-ruby-sass. doesn't use ruby implementation of sass, rather c implementation (libsass). allows use .pipe() other gulp plugins:

var sass = require('gulp-sass');  gulp.task('sass', function () {   return gulp.src('./app/template/css/style_v1.scss')     .pipe(sass())     .on('error', function (err) { console.log(err.message); })     .pipe(gulp.dest('./dist/css'))     .pipe(livereload()); });