A QUICK GUIDE TO PROGRAMMING FOR THE WEB. ssh (then type your UBIT password when prompted)

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1 A QUICK GUIDE TO PROGRAMMING FOR THE WEB TO GET ACCESS TO THE SERVER: ssh Secure- Shell. A command- line program that allows you to log in to a server and access your files there as you would on your own computer. Sample usage (for Gamera): ssh username@gamera.caset.buffalo.edu (then type your UBIT password when prompted) After logging in, you can run commands from the command-line as you normally would. Don t know any? This should help SOME BASIC UNIX/COMMAND-LINE FUNCTIONS YOU SHOULD KNOW: man consult the built- in manual about a given function man cp (show the manual page for cp ) ls list all the files in the current directory. ls -al (provide a complete listing of all files in the current directory, including invisible files) ls *.jpg (list all files that end in.jpg) cd change directories, navigate through the tree file system cd ~ (move into your home directory) cd / (move into your system s root directory) cd public_html (move into your html directory)

2 cp copy a file, create a renamed copy of a file cp thisfile../thisfilecopy (copying a file into the directory above this one in the tree structure that is, the folder containing the folder you re currently in.) cp thisotherfile thisotherfilecopy (create a copy of a file in the same directory) mv move a file from one location to another, rename a file while deleting the original. mv somefile../somefile (move a file into the previous directory in the tree) mv somefile newname (rename a file) rm delete a file rm somefile (delete some file.) pwd print your current location (absolute path) pwd (where am I?) sftp Secure File Transfer Protocol. A command- line program that allows you to upload files to and download files from a server. Sample usage (for Gamera): sftp username@gamera.caset.buffalo.edu (type your UBIT password when prompted) To upload a file: put filename target_directory To download a file: get filename local_computer_directory get filename. (download file to your current local directory)

3 A NOTE:. shortcut meaning the current directory.. shortcut meaning the directory above the one I m currently in TO ACCESS A DATABASE ONCE CONNECTED TO THE SERVER (via ssh): mysql Command- line interpreter for the MySQL database language. Use this to create a database if it doesn t need to be created dynamically, to debug MySQL code if you re getting strange errors, and to check and make sure your tables are being accessed/changed/etc. appropriately. An important point about MySQL unlike SQLite, MySQL uses a server- client framework. This means that databases are stored on a server, and a client is used to access them. Part of this model is that you must use a username and password to connect to the MySQL server you ll see this in the PHP code below. Some useful commands: show users; (Show all registered users useful to verify if the username that you re using in your PHP code to connect to the MySQL server) show databases; (Show all databases useful to verify if your database has been successfully created.) using some_database; (Select a database to work with if you re working mostly in PHP, you won t need this, but if you re working on the command line, it s necessary.) If using Gamera, your username and database must be created by a system administrator. If using your own webserver, you re generally able to create and administrate this yourself (sometimes through GUI tools). The rest of MySQL uses a nearly identical syntax to SQLite. USING PHP WITH MYSQL: Note that all PHP code is enclosed in and symbols. Otherwise, the syntax is similar to C++, Javascript, and Processing.

4 PHP is weakly typed, meaning that the types of variables do not need to be specified and is calculated on- the- fly. It is an interpreted scripting language, similar to Python. It is a server- side language, which means that all PHP code is interpreted and executed by the server before the document is sent to the user/client. This limits some of the kinds of interactions that can occur between server and client. A basic HTML page that uses PHP the page uses forms to request a user s name and age, then prints a greeting when the submit button is clicked: if ($_POST["fname"] == null) { $printform = true; else { $printform = false; <html> <head> <title>my Cool First Webpage</title> </head> <body> <a href=" text</a> if (!$printform) { echo "<!--"; <form action="index.php" method="post"> Name: <input type="text" name="fname" /> Age: <input type="text" name="age" /> <input type="submit" /> </form> if (!$printform) { echo "-->"; echo "Hello ". $_POST["fname"].", who is ".$_POST["age"]." years old!"; </body> </html> A basic example of parsing form data and inserting it into a MySQL database.

5 To use this, your initial form HTML element (such as the one above) would be as follows: <form action="receive.php" method="post"> //upload data to a database using POST data from a webform (or something else) $date = $_POST["date"]; $time = $_POST["time"]; $location = $_POST["location"]; $con = mysql_connect('localhost','someusername','password'); if (!$con) { die('could not connect: '. mysql_error()); $result = mysql_select_db('some_database', $con); if (!$result) { die('could not select database'. mysql_error()); $query = "INSERT INTO some_table (date, time, location) VALUES ('$date', '$time', '$location')"; $result = mysql_query($query); if (!$result) { die('could not insert'. mysql_error()); For more information on using PHP with MySQL, check out the following tutorial: