ack "ini_set" /path/to/piwik/
index.php
19:@ini_set('display_errors', (!defined('PIWIK_DISPLAY_ERRORS') || PIWIK_DISPLAY_ERRORS) ? 1 : 0);
20:@ini_set('xdebug.show_exception_trace', 0);
21:@ini_set('magic_quotes_runtime', 0);

piwik.php
23:@ini_set('xdebug.show_exception_trace', 0);
24:@ini_set('magic_quotes_runtime', 0);

plugins/Referers/Controller.php
373:	@ini_set("default_socket_timeout", $timeout = 1);
409:			@ini_set("default_socket_timeout", $timeout = 1);

libs/Smarty/Config_File.class.php
240:        ini_set('track_errors', true);

libs/PEAR.php
55:@ini_set('track_errors', true);

libs/Zend/Session.php
205:                    ini_set("session.$defaultOptionName", $defaultOptionValue);
219:                ini_set("session.$userOptionName", $userOptionValue);

libs/Zend/Feed.php
262:        @ini_set('track_errors', 1);
302:        @ini_set('track_errors', 1);

libs/Zend/Feed/Reader.php
382:        @ini_set('track_errors', 1);
444:            @ini_set('track_errors', 1);

libs/Zend/Feed/Entry/Atom.php
195:        @ini_set('track_errors', 1);

libs/Zend/Feed/Entry/Abstract.php
81:                @ini_set('track_errors', 1);

libs/Zend/Feed/Abstract.php
112:        @ini_set('track_errors', 1);

core/Mail.php
65:		ini_set("smtp_port", $config->port);

core/Piwik.php
896:		@ini_set('max_execution_time', $executionTime);
947:			|| ($currentValue < $minimumMemoryLimit	&& @ini_set('memory_limit', $minimumMemoryLimit.'M')))

core/Session.php
29:		@ini_set('session.use_cookies', '1');
32:		@ini_set('session.use_only_cookies', '1');
37:			@ini_set('session.cookie_secure', '1');
41:		@ini_set('session.cookie_httponly', '1');
45:		@ini_set('session.name', $sessionName);
49:		@ini_set('session.referer_check', '');
72:			@ini_set('session.gc_probability', 1);

core/testMinimumPhpVersion.php
57:	if(!function_exists('ini_set'))
59:		$piwik_errorMessage .= "<p><b>Piwik and Zend_Session require the <code>ini_set()</code> function</b></p>
61:					To enjoy Piwik, you need remove <pre>ini_set</pre> from your <pre>disable_functions</pre> directive in php.ini.</p>";

core/Http.php
305:			@ini_set('default_socket_timeout', $timeout);
354:				@ini_set('default_socket_timeout', $default_socket_timeout);