PHP is an open source server side scripting Language which originally stood for ‘Personal Home Page‘ now stands for ‘PHP: Hypertext Preprocessor‘, which is a recursive acronym. It is a cross platform scripting language which is highly influenced by C, C++ and Java.

PHP is HTML embedded script which facilitates developers to write dynamically generated pages quickly. PHP is primarily used on Server-side (and JavaScript on Client Side) to generate dynamic web pages over HTTP.

In this we focus  on the command-line aspect of PHP scripting Language.-

1. After PHP and Apache2 installation, we need to install PHP command Line Interpreter.

# apt-get install php5-cli    [Debian and alike System)
# yum install php-cli     [CentOS and alike System)

Next thing, we do is to test a php (if installed correctly or not) commonly as by creating a file infophp.php at location ‘/var/www/html‘ (Apache2 working directory in most of the distros), with the content , simply by running the below command.

# echo '' > /var/www/html/infophp.php

and then point your browser to http://127.0.0.1/infophp.php which opens this file in web browser.

Same results can be obtained from the Linux terminal without the need of any browser. Run the PHP file located at ‘/var/www/html/infophp.php‘ in Linux Command Line as:

# php -f /var/www/html/infophp.php

Since the output is too big we can pipeline the above output with ‘less‘ command to get one screen output at a time, simply as:

# php -f /var/www/html/infophp.php | less

Here Option ‘-f‘ parse and execute the file that follows the command.

2. We can use phpinfo() which is a very valuable debugging tool directly on the Linux command-line without the need of calling it from a file, simply as:

# php -r 'phpinfo();'

Here the option ‘-r‘ run the PHP Code in the Linux Terminal directly without tags < and >.

3. Run PHP in Interactive mode and do some mathematics. Here option ‘-a‘ is for running PHP in Interactive Mode.

# php -a

Interactive shell

php > echo 2+3;
5
php > echo 9-6;
3
php > echo 5*4;
20
php > echo 12/3;
4
php > echo 12/5;
2.4
php > echo 2+3-1;
4
php > echo 2+3-1*3;
2
php > exit

Press ‘exit‘ or ‘ctrl+c‘ to close PHP interactive mode.

4. You can run a PHP script simply as, if it is a shell script. First Create a PHP sample script in your current working directory.

# echo -e '#!/usr/bin/php\n' > phpscript.php

Notice we used #!/usr/bin/php in the first line of this PHP script as we use to do in shell script (/bin/bash). The first line #!/usr/bin/php tells the Linux Command-Line to parse this script file to PHP Interpreter.

Second make it executable as:

# chmod 755 phpscript.php

and run it as,

# ./phpscript.php

5. You will be surprised to know you can create simple functions all by yourself using the interactive shell. Here is the step-by step instruction.

Start PHP interactive mode.

# php -a

Create a function and name it addition. Also declare two variables $a and $b.

php > function addition ($a, $b)

Use curly braces to define rules in between them for this function.

php > {

Define Rule(s). Here the rule say to add the two variables.

php { echo $a + $b;

All rules defined. Enclose rules by closing curly braces.

php {}

Test function and add digits 4 and 3 simply as :

php > var_dump (addition(2,3));

Output -

5NULL

You may run the below code to execute the function, as many times as you want with different values. Replace a and b with values of yours.

php > var_dump (addition(a,b));

php > var_dump (addition(9,3.3));

Output

12.3NULL

You may run this function till you quit interactive mode (Ctrl+z). Also you would have noticed that in the above output the data type returned is NULL. This can be fixed by asking php interactive shell to return in place of echo.

Simply replace the ‘echo‘ statement in the above function with ‘return‘

Replace

php { echo $a + $b;

with

php { return $a + $b;

and rest of the things and principles remain same.