Both pear and pecl tools should be available everywhere on command line. For that to work, pear's binary (bin) directory should be in your PATH variable.

To verify it works, simply type pear. A list of commands should be shown:

$ pear
Commands:
build                  Build an Extension From C Source
bundle                 Unpacks a Pecl Package
channel-add            Add a Channel
...

You should further test that PEAR is up to date:

$ pear version
PEAR Version: 1.7.2
PHP Version: 5.2.6RC4-pl0-gentoo
Zend Engine Version: 2.2.0
Running on: Linux ...

To use PEAR and PEAR compatible packages in your applications, you normally include them into your PHP scripts using require_once(). For this to work, PEAR's php_dir must be a part of PHP's include path.

1. First, check where PEAR installs .php files:

   $ pear config-get php_dir
   /usr/share/lib/php/

   This directory will contain System.php.

2. Now it's time to find which configuration file is used by your PHP installation. On command line, execute:

   $ php --ini
   Configuration File (php.ini) Path: /etc/php/cli-php5
   Loaded Configuration File:         /etc/php/cli-php5/php.ini
   Scan for additional .ini files in: /etc/php/cli-php5/ext-active
   Additional .ini files parsed:      /etc/php/cli-php5/ext-active/php_gtk2.ini,
   /etc/php/cli-php5/ext-active/xdebug.ini

   To see which php.ini is used by PHP on your web server, create a file with only <?php phpinfo(); ?> as the contents, and save it in your local web root as check_php.php. Open the file in your browser as http://localhost/check_php.php, to find the path to the php.ini file your web server is using.

3. Now check PHP's include_path setting on command line:

   $ php -c /path/to/php.ini -r 'echo get_include_path()."\n";'

   To check PHP's include_path in your web server, create a file with only <?php phpinfo(); ?> as the contents, and save it in your local web root as check_php.php. Open the file in your browser as http://localhost/check_php.php, to verify the include_path your web server is using.

   In every case, PEAR's php_dir should be in the include path. If not, add it in your system's php.ini.

4. Now that this is done, try including a file. Create a new check_pear.php file with the following contents:

   <?php
require_once 'System.php';
var_dump(class_exists('System', false));
?>

   System.php is shipped with every PEAR installation and thus should be on your computer, too. Open the file with the browser from your web server, and also try it on command line. The only output should be

   bool(true)

   A message like:

   
   Warning: require_once(System.php): failed to open stream:
    No such file or directory in /path/to/check_pear.php on line 2
      

   means that your include path is not correct. (So go and fix it!)

   A completely white page in your browser hints two things:

   • Your server is configured to not display any errors to the user/browser (display_errors Off)

   • There was an error including System.php, and you should check you server's error log.

That's it! Now go on and install some packages.

include_path="."

; Unix
include_path=".:/usr/local/php/pear/"

; Windows
include_path=".;C:\php\pear\"