PHP Knowledge Base Update -- July 5th, 1999

I'm amazed at the quantity and quality of the information on the PHP mailing list everyday. Although a lot of questions are now covered in the knowledge base these summaries don't seem to be getting any shorter... Thanks to everyone who contributes their knowledge and time to the list, making these summaries possible. Cheers, Nathan ------------------------------------------------------------ Can I use PHP to add a new user and password to my Unix system? How can I add a new user to my FreeBSD system using PHP? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/393 ------------------------------------------------------------ Karl Pielorz Try exec'ing 'adduser' from PHP. For more information on adduser do this at the unix command line: man adduser For security's sake make sure you do some sensible checking / protection for the parameters. ------------------------------------------------------------ Can I use variable function names in PHP? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/395 ------------------------------------------------------------ Nathan Wallace Try something like the following: $fn_name = 'myfunc'; $result = $fn_name($arg1, $arg2); Then the function called myfunc (specified in the variable $fn_name) will be called. ------------------------------------------------------------ Why can't I see the contents of my cookie in a function? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/396 ------------------------------------------------------------ Nathan Wallace PHP treats every variable as local to the function unless you specify it as global. Thus, you cannot access $HTTP_COOKIE_VARS in a function unless you declare it as global inside that function. This should work: function ReadCookie($name) { global $HTTP_COOKIE_VARS; return $HTTP_COOKIE_VARS[$name]; } Similarly the cookie is not accessable by name unless you declare it as global. In this case what we actually want is the variable that holds the cookie (the one called $name) to be global, so we have to globalize the variable variable... function ReadCookie($name) { global $$name return $$name; } ------------------------------------------------------------ Can I run a Javascript function automatically when someone leaves the page? How can I know that a user has left a page? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/397 ------------------------------------------------------------ Jason Brooke Once the browser finishes sending the page to the client, the state ends there. Any session management features of a scripting language can then only use cookies or a unique id passed in the query string or form fields to identify the client on the next request. The only thing you might be able to do is to use the javascript onUnload() function to cause a form submission which might send something back to your server. ------------------------------------------------------------ What is the client server sequence for setting a cookie? How can I check if a browser accepts cookies? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/399 ------------------------------------------------------------ Nathan Wallace Here is the cookie setting sequence in PHP: Client Server requests page gets request sets cookie in reply sends reply gets reply (with cookie) sets cookie on machine sends new request (with cookie included) gets request finds cookie in request sets variable in script runs script The server has to interact with the client to be able to set a cookie or determine if it has been set. ------------------------------------------------------------ How can I stop text from wrapping in a browser? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/401 ------------------------------------------------------------ Nathan Wallace Try using the HTML <pre> tags. Anything between them will be shown in the browser with the exact formatting (including line breaks) that you specify. <pre> <?php echo "I should be a really long line that we don't want to wrap..."; ?> </pre> ------------------------------------------------------------ How can I work out the days in a month? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/402 ------------------------------------------------------------ Chuck Hagenbuch From the manual: http://www.php.net/manual/function.date.php3 the option to use is: t - number of days in the given month; i.e. "28" to "31" so your code looks like: $days_this_month = date('t'); // specify a timestamp if you want a different month ------------------------------------------------------------ How can I tell if the user has aborted the download? How can I force a script to execute completely even if the user aborts? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/403 ------------------------------------------------------------ Rasmus Lerdorf Add connection_status() function. This returns the raw bitfield which indicates whether the script terminated due to a user abort, a timeout or normally. Note that if ignore_user_abort is enabled, then both the timeout state and the user abort state can be active http://www.php.net/manual/function.connection-status.php3 Add connection_timeout() function. This one can be called in a shutdown function to tell you if you got there because of a timeout http://www.php.net/manual/function.connection-timeout.php3 Add ignore_user_abort() function and .ini/.conf directive of same name http://www.php.net/manual/function.ignore-user-abort.php3 Fix connection abort detection code - It should now work reliably with Apache. Also added a user-level connection_aborted() function designed to let people check whether the user aborted the connection in a user-level shutdown function. http://www.php.net/manual/function.connection-aborted.php3 Here is the test script as used by Rasmus when writing the functions: <? set_time_limit(5); ignore_user_abort(0); register_shutdown_function("done"); function done() { global $i, $fp; fputs($fp,"i reached $i\n"); if(connection_aborted()) fputs($fp,"** the connection was aborted **\n"); fclose($fp); echo "all done\n"; } $fp = fopen("/tmp/done","w"); for($i=0; $i<7; $i++) { fputs($fp,"i is $i\n"); for($j=0;$j<1000;$j++) $a=sqrt($j); sleep(1); echo "$i ................................................................................<br>"; flush(); } exit; ?> This should give you some ideas. ------------------------------------------------------------ What type of password does imap_open() expect? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/405 ------------------------------------------------------------ Mark Musone imap_open expects a plaintext password. For more information see the manual: http://www.php.net/manual/function.imap-open.php3 ------------------------------------------------------------ Are there any resources for Italian developers? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/406 ------------------------------------------------------------ Michel Morelli There is an Italian mailing list available for php3 Send an email with subscribe as the subject to the address php3-it-request@michel.enter.it to join. ------------------------------------------------------------ How can I get the users time? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/407 ------------------------------------------------------------ Teodor Cimpoesu You can try guessing his timezone (TZ) based on the country code given by REMOTE_ADDR, and set the time acordingly. ------------------------------------------------------------ Why is my httpd binary very big with PHP installed? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/408 ------------------------------------------------------------ M.Brands, Jerry Preeper Your new version might still contain debugging information? You can check this by doing file <filename> Ofcourse, <filename> needs to be replaced by the full name of you httpd binary. If file says the file is not stripped (i.e. it still contains debuginfo), you can strip that debuginfo by doing strip <filename> Ofcourse, if you run into problems later, it will be impossible to debug things. But it doesn't happen very often that you need to debug PHP itself. That's more something for PHP developers (like Zeev and Andy) or beta testers. ------------------------------------------------------------ How can I check the size of a file on the client side? How can I limit the size of files uploaded to the server by a user? http://e-gineer.com/e-gineer/phpkb/view.phtml/qid/409 ------------------------------------------------------------ Mitch Vincent, John Coggeshall Javascript does not allow operations on files, and so it is not possible to check the size of a file on the client side. Most people checking the size of a file will want to do so before the user uploads the file to their server. You cannot actually do this until the file upload is in progress. You can put a MAXFILESIZE HTML tag in the <INPUT TYPE="file"> tag... Or you can check the filesize once it's uploaded to PHP and simply not process the upload if it's too big or too small (the file will be automatically deleted after your script exits)....