Yep, it's there in PHP 5.2's cli SAPI.

If you cannot upgrade and that's the case that there's no such option in PHP 5.2 (I don't have it at hand to test), you can do this:

echo "<?php echo \"hi\\n\";" | php

hi

Original:

There is indeed a -r option (though I'm not sure about PHP 5.2):

php -r "echo 'hi';";

hi

Just make sure you are using the command line version of PHP. php --version should give you something like this (notice "cli"):

php --version

PHP 5.3.0 (cli) (built: May 20 2010 19:05:12) (DEBUG)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2009 Zend Technologies

If you're going to do PHP in the command line, I recommend you install phpsh, a decent PHP shell. It's a lot more fun.

Anyway, the php command offers two switches to execute code from the command line:

-r <code>        Run PHP <code> without using script tags <?..?>
-R <code>        Run PHP <code> for every input line

You can use php's -r switch as such:

php -r 'echo function_exists("foo") ? "yes" : "no";'

The above PHP command above should output no and returns 0 as you can see:

>>> php -r 'echo function_exists("foo") ? "yes" : "no";'
no
>>> echo $? # print the return value of the previous command
0

Another funny switch is php -a:

-a               Run as interactive shell

It's sort of lame compared to phpsh, but if you don't want to install the awesome interactive shell for PHP made by Facebook to get tab completion, history, and so on, then use -a as such:

>>> php -a
Interactive shell

php > echo function_exists("foo") ? "yes" : "no";
no

If it doesn't work on your box like on my boxes (tested on Ubuntu and Arch Linux), then probably your PHP setup is fuzzy or broken. If you run this command:

php -i | grep 'API'

You should see:

Server API => Command Line Interface

If you don't, this means that maybe another command will provides the CLI SAPI. Try php-cli; maybe it's a package or a command available in your OS.

If you do see that your php command uses the CLI (command-line interface) SAPI (Server API), then run php -h | grep code to find out which crazy switch - as this hasn't changed for year- allows to run code in your version/setup.

Another couple of examples, just to make sure it works on my boxes:

>>> php -r 'echo function_exists("sg_load") ? "yes" : "no";'
no
>>> php -r 'echo function_exists("print_r") ? "yes" : "no";'
yes

Also, note that it is possible that an extension is loaded in the CLI and not in the CGI or Apache SAPI. It is likely that several PHP SAPIs use different php.ini files, e.g., /etc/php/cli/php.ini vs. /etc/php/cgi/php.ini vs. /etc/php/apache/php.ini on a Gentoo Linux box. Find out which ini file is used with php -i | grep ini.

PHP is most often interpreted (it can be compiled but that's often more work than it's worth). So the way your running PHP is the best and most straight forward way to run PHP via commandline. If you really dislike including php every time your can include #!/usr/bin/php at the beginning of the file and then run them directly. Before you can run them make sure to set the execute flag > chmod +x helloworld.php.

#!/usr/bin/php
<?php
echo "hello world";
?>

> helloworld.php