ng serve not detecting file changes automatically : <p>I need to run <code>ng serve</code> every time when any changes made to the source files.I have no error in the console.</p>

<pre><code>Angular CLI: 1.6.2
Node: 8.9.1
OS: linux ia32
Angular: 5.1.2
... animations, common, compiler, compiler-cli, core, forms
... http, language-service, platform-browser
... platform-browser-dynamic, router

@angular/cdk: 5.0.2-c3d7cd9
@angular/cli: 1.6.2
@angular/material: 5.0.3-e20d8f0
@angular-devkit/build-optimizer: 0.0.36
@angular-devkit/core: 0.0.22
@angular-devkit/schematics: 0.0.42
@ngtools/json-schema: 1.1.0
@ngtools/webpack: 1.9.2
@schematics/angular: 0.1.11
@schematics/schematics: 0.0.11
typescript: 2.4.2
webpack: 3.10.0
</code></pre>
