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Digg  getmypid
Gets PHP's process ID
(PHP 4, PHP 5)
Code Examples / Notes » getmypidpure-php
You can use this function also to avoid more than one instance of your app. You can also use this class. http://www.pure-php.de/node/20 Usage: <?php inlude("ProcessHandler.class.php"); if(ProcessHandler::isActive()){ die("Already running!\n";); }else{ ProcessHandler::activate(); //run my app } ?> barry
Why dont use use uniqid() to get a unique serial nr for security purposes? Or md5(uniqid()), for extra fun. Check http://www.php.net/uniqid for more about this.. 10-sep-2002 10:46
Something you can use to combine several weak entropy sources, into a better init value for srand() and mt_srand(): mt_srand(time() ^ (int)microtime() ^ ip2long($_SERVER['REMOTE_ADDR']) ^ (int)$_SERVER['REMOTE_PORT'] ^ @getmypid() ^ @disk_free_space('/tmp') ); Note that getmypid() may return 0 on some shared PHP installations that have excluded it for "safe"... The safe mode also exclude the disk_free_space(directory) function call in some cases, for security reason. This explains the use of the @ operator to ignore warnings... the directory should be a highly active directory, which is accessible and typically used for temporary contents generated by PHP. The above code combines all these sources using XOR binary operations, to avoid 32-bit overflows. brooke
One good use for this is deciding on a concurrency-safe temporary file or directory name. You can be assured that no two processes on the same server have the same PID, so this is enough to avoid collisions. For example: $tmpfile = "/tmp/foo_".getmypid(); // Use $tmpfile... // Use $tmpfile... // Use $tmpfile... unlink ($tmpfile); If you are sharing /tmp over the network (which is odd....) then you can, of course, mix in the PHP server's IP address. carl
As it is very unlikely today that there will be two PHP processes with the same process ID within the same microsecond, this function can be used for something like srand((int)microtime() ^ getmypid() ^ time()) to have a decent chance of avioding a collision. Just relying on the time in microseconds is a rather Bad Thing to do, since a contect switch might very well take a lot less than that, so there's a decent chance of two simultaneous request to get the same ID. If you're running your php script upon an HTTP request, you might even want to toss in the IP addy of the remote host in your seed for a bit of extra entropy. You can't be too paranoid when it comes to 'random' numbers. (Side note: I tried using hardware to generate random numbers, but with my setup it took just about forever to gather enough entropy. All hail ran3()! ) kroczu
<? /* mixed getpidinfo(mixed pid [, string system_ps_command_options]) this function gets PID-info from system ps command and return it in useful assoc-array, or return false and trigger warning if PID doesn't exists $pidifo=getpidinfo(12345); print_r($pidifo); Array ( [USER] => user [PID] => 12345 [%CPU] => 0.0 [%MEM] => 0.0 [VSZ] => 1720 [RSS] => 8 [TT] => ?? [STAT] => Is [STARTED] => 6:00PM [TIME] => 0:00.01 [COMMAND] => php someproces.php > logfile ) */ ////////////////////////////////////////////// function getpidinfo($pid, $ps_opt="aux"){ $ps=shell_exec("ps ".$ps_opt."p ".$pid); $ps=explode("\n", $ps); if(count($ps)<2){ trigger_error("PID ".$pid." doesn't exists", E_USER_WARNING); return false; } foreach($ps as $key=>$val){ $ps[$key]=explode(" ", ereg_replace(" +", " ", trim($ps[$key]))); } foreach($ps[0] as $key=>$val){ $pidinfo[$val] = $ps[1][$key]; unset($ps[1][$key]); } if(is_array($ps[1])){ $pidinfo[$val].=" ".implode(" ", $ps[1]); } return $pidinfo; } ?> webmaster
$_SERVER['REMOTE_ADDR'] is a bad thing to use these days. Since AOL, and MSN Browsers change the IP address at the most uncomfortable times, such as going from unsecure to secure mode, you cannot rely on it staying the same anymore. Using this Octal-Quad for hanging on to a user, such as in shopping carts will ALWAYS FAIL with AOL browsers. FYI. |
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assert_options assert dl extension_loaded get_cfg_var get_current_user get_defined_constants get_extension_funcs get_include_path get_included_files get_loaded_extensions get_magic_quotes_gpc get_magic_quotes_runtime get_required_files getenv getlastmod getmygid getmyinode getmypid getmyuid getopt getrusage ini_alter ini_get_all ini_get ini_restore ini_set main memory_get_peak_usage memory_get_usage php_ini_scanned_files php_logo_guid php_sapi_name php_uname phpcredits phpinfo phpversion putenv restore_include_path set_include_path set_magic_quotes_runtime set_time_limit sys_get_temp_dir version_compare zend_logo_guid zend_thread_id zend_version |
