title: GULP: set variables or arguments
body: <p>I've this snippet code:</p>
  
  <pre><code>gulp.src('src/index-public.html').pipe(rename('index.html'))
      .pipe(replace("&lt;base href='/'&gt;", function(match) {
          return'&lt;base href="/web/"&gt;'
      }))
  </code></pre>
  
  <p>As you can see I'm replacing <code>"base href='/'&gt;"</code> by <code>"base href='/web'"</code>.</p>
  
  <p>I need to replace <code>"base href='/'&gt;"</code> by <code>"base href='/${ARGUMENT OR ENV VARIABLE}'"</code></p>
  
  <p>I've tried using <code>gulp --basehref "web"</code> but it doesn't work.</p>
  
  <p>Any ideas?</p>