How to invention login url as the same facebook?
<p>How to invention login url  as the same facebook ?(PHP)</p>

<p><strong>+ Example</strong></p>

<pre><code>www.abc.com
</code></pre>

<p><strong>+After login</strong></p>

<p><em>user=a1</em></p>

<pre><code>www.abc.com/a1/index.php
</code></pre>

<p><em>user=a2</em></p>

<pre><code>www.abc.com/a2/index.php
</code></pre>

<p>How to invent this in <strong>PHP</strong>?</p>
