DOMPDF is software written in PHP which allows you to export HTML pages to PDF. Follow these instructions to download and install DOMPDF. In this tutorial, I will explain how to use DOMPDF on a Linux Web server.

Because of the many dependencies needed by DOMPDF, I usually recommend using other options, such as HTML2PS. HTML2PS is very easy to installl on Linux, using apt-get install or yum install. On the other hand, following is a list of dependencies needed by DOMPDF. HTML2PS also has better support for CSS.

• PHP version 5 or higher
• php-mbstring (not available using apt-get install or yum install; download rpm)
• php-common
• lib.so.6() (64bit)
• lib.so.6(GLIB_2.2.5) (64bit)
• lib.so.6(GLIB_2.3.4) (64bit)
• lib.so.6(GLIB_2.3) (64bit)
• lib.so.6(GLIB_2.4) (64bit)
• libpthread.so.0() (64bit)
• rtld(GNU_HASH)
• DOM

In order to use DOMPDF, you need to be running PHP version 5 or higher. To determine the version of PHP being run on your Web server, go to http://www.yourdomain.com/phpinfo.php. You also will need the mbstring extension and the DOM extension. 

1. Download the DOMPDF package from https://github.com/dompdf/dompdf/releases. Because this tutorial is for Linux, we would download the .tar.gz package.
2. Extract the contents of the tar gunzip using this command:

tar -zxvf dompdf-version.tar.gz -C /path/to/web/server/root

3. Remove the origial tar gunzip file.

rm dompdf-version.tar.gz

4. Add the followiing markup to the PHP page you want to add the export to PDF option.

<form method="post" action="stage.php">
  <textarea name="content" id="content"></textarea>
  <br />
  <input type="submit" name="submit" id="submit" value="create pdf">
</form>

<?php
include ('dompdf-version/dompdf_config.inc.php');

if(isset($_POST['submit'])) 
{
  $content = $_POST['content'];
  $dompdf = new DOMPDF();
  $dompdf->load_html($content);
  $dompdf->render();
  $dompdf->stream('example.pdf');
}
?>