Programming Language, Scripting Language

PHP (recursive acronym for "PHP: Hypertext Preprocessor") is a widely-used Open Source general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.





Extract from

In case of setting up the server and PHP on your own, you have two choices for the method of connecting PHP to the server. For many servers PHP has a direct module interface (also called SAPI). These servers include Apache, Microsoft Internet Information Server, Netscape and iPlanet servers. Many other servers have support for ISAPI, the Microsoft module interface (OmniHTTPd for example). If PHP has no module support for your web server, you can always use it as a CGI or FastCGI processor. This means you set up your server to use the CGI executable of PHP to process all PHP file requests on the server.

If you are also interested to use PHP for command line scripting (e.g. write scripts autogenerating some images for you offline, or processing text files depending on some arguments you pass to them), you always need the command line executable. For more information, read the section about writing command line PHP applications. In this case, you need no server and no browser.

A blog from 2012-09-03 describes differences between three variants (Apache, CGI, and FastCGI) and also a fourth (PHP FPM) is mentioned in comments.

string php_sapi_name ( void ): cgi-fcgi, 3

  Apache Module CGI FastCGI PHP FPM Other Server PHPs Own Server CLI Unsure
In use now (cgi-fcgi)  No   No  Yes  No   No   No   No   No 
PHP Interpreter Embedded in each Apache process External External          
PHP config in .htaccess file(s) Yes ? No          

General research

Specific modes research

  1. Direct module interface (SAPI or ISAPI)
  2. CGI
  3. FastCGI
  4. PHP FPM (FastCGI Process Manager)
  5. cadium
  6. cli
  7. cli_server
  8. continuity
  9. embed
  10. litespeed




A few examples

Hello, World!
(in html-format)
> Execute
(sep. win/tab)
print "<html><head><title>Hello, World! Script</title></head>\n";
print "<body>\n";
print "<p>Hello, World!</p>\n";
print "</body></html>\n";

Output from phpinfo(1).
A little bit more advanced
example showing some
> Execute
(sep. win/tab)

ob_start(); // start output buffer, => nothing's displayed until buffer's closed
phpinfo(1); // Show just general information (1)
$php_info .= ob_get_contents();
$php_info = str_replace("</body></html>", "", $php_info);
$offset   = strpos($php_info, "<table");
print substr($php_info, $offset);


Environment tests

  Method Result Comments
PHP Version phpversion() 7.4.33  
short_open_tag ini_get('short_open_tag') 1 Prefer Not Set - easier and clearer handling of mixed PHP (<?php) and XML (<?xml).
  Safe technique short_open_tag
Code: <?php echo "$test";?> <?=$test?>
Output: Yes! Yes!

"Since PHP 5.4.0, <?= is always available." [src]


Version in use (7.4.33) is newer than 5.4
Timezone get_cfg_var('date.timezone')



Checks if Exists

Checks if something exists in current environment:

Example, static data, a good/true test result: Yes  
Example, static data, a bad/false test result:  No   
The following rows are now live data, retrieved when page was loaded ###, and reflects the current runtime environment.
PHP version: 7.4.33
core module, extension_loaded('core') Yes (Always, unless major - major - problem...)
gd extension'module, extension_loaded('gd') Yes (Always, unless major - major - problem...)
PECL module  No  extension_loaded('pecl')
function locale_parse(): Yes function_exists("locale_parse")
string locale_get_default ( void ): Yes function_exists("locale_get_default"),
bool  ( string $class_name [, bool $autoload = true ] ) Yes class_exists("locale")


Error Handling

$my_error_reporting_enable = 1 (in script)

Code Live result (2023-04-01T21:59:05-0400)
<?php echo $some_undefined_variable;?>

Notice: Undefined variable: some_undefined_variable in /homepages/41/d105562370/htdocs/comgt-com/lib/php/index.php on line 544
Missing file,
<?php include "some-non-existing-file.php"; ?>

Warning: include(some-non-existing-file.php): failed to open stream: No such file or directory in /homepages/41/d105562370/htdocs/comgt-com/lib/php/index.php on line 548

Warning: include(): Failed opening 'some-non-existing-file.php' for inclusion (include_path='.:/usr/lib/php7.4') in /homepages/41/d105562370/htdocs/comgt-com/lib/php/index.php on line 548

From / manual / en / errorfunc.configuration.php (R:2016-02-29):

Errors and Logging Configuration Options
Name Default Changeable Changelog This System
error_reporting NULL PHP_INI_ALL   22517
display_errors "1" PHP_INI_ALL   (Not set)
display_startup_errors "0" PHP_INI_ALL   (Not set)
log_errors "0" PHP_INI_ALL   (Not set)
log_errors_max_len "1024" PHP_INI_ALL Available since PHP 4.3.0. (Not set)
ignore_repeated_errors "0" PHP_INI_ALL Available since PHP 4.3.0. (Not set)
ignore_repeated_source "0" PHP_INI_ALL Available since PHP 4.3.0. (Not set)
report_memleaks "1" PHP_INI_ALL Available since PHP 4.3.0. (Not set)
track_errors "0" PHP_INI_ALL   (Not set)
html_errors "1" PHP_INI_ALL PHP_INI_SYSTEM in PHP <= 4.2.3. (Not set)
xmlrpc_errors "0" PHP_INI_SYSTEM Available since PHP 4.1.0. (Not set)
xmlrpc_error_number "0" PHP_INI_ALL Available since PHP 4.1.0. (Not set)
docref_root "" PHP_INI_ALL Available since PHP 4.3.0. (Not set)
docref_ext "" PHP_INI_ALL Available since PHP 4.3.2. (Not set)
error_prepend_string NULL PHP_INI_ALL   (Not set)
error_append_string NULL PHP_INI_ALL   (Not set)
error_log NULL PHP_INI_ALL   (Not set)
Additional, by COMGT:        
zend_extension = "" (php.ini)   (Enhanced error handling) (Not set)

Some research


Environment Variables

how to get client's IP address in PHP -

reserved variables -


mail - send mail (send emails)

(PHP 4, PHP 5) mail — Send mail, man page:


( )


Problems and Solutions

Until further notice, pls see Perl-section for more troubleshooting in general.

php-and-ssi.php - tests


Shell Scripts in PHP

If want to create scripts for use both in web server but also maybe occasionally as scripts.

!/usr/bin/env php

print "<html><head><title>Printenv Script</title></head>\n";
print "<body>\n";
print "Hello, World, in PHP";
print "</body></html>\n";

Important details:

1) Shebang as first line
2) (Apparently) Also must have '<?php' .. '?>' also in scripts, to work what so ever.
3) Make sure executable (e.g. chmod a+x)

Note: Difference in how works on 1&1:

With '!/usr/bin/php ' as shebang:

(uiserver):uXXX:~/comgt-com/... > ./printenv.php
X-Powered-By: PHP/4.4.9
Content-type: text/html

With '!/usr/bin/env php ' as shebang:

(uiserver):uXXX:~/comgt-com/... > ./
X-Powered-By: PHP/5.5.30
Content-type: text/html


Testing Scripts

Click to see how the web server handles different potential issues, details that may differ on different servers. All opens in a separate window (or tab).

Script Description
printhello.php Hello, World! program
phpinfo.php print lots of info about runtime environment

More extensive tests of scripts are also avaiable in the Perl-section, including one page running a number of scripts (mostly Perl).

Older Material / Archive

Macintosh Notes

(Added 2009-09-08)

Standard installation - that is part of standard Mac OS X 10.6 - still isn't including (e.g.) mcrypt.

(Compare what was installed 2009-09-08 on MacMini (PHP 5.2.9, Entropy release 7) and standard OS X 10.6 (PHP 5.3.0). See all saved static phpinfo() results. Note: MacMini config retrieved via

Better to download and install Entropy's (which did earlier on Mac OS X 10.5).


Download (v5.3.0): (53.4 MB, can take quite a while... At least half hour. Seems like Entropy has a slow server - other communications are working quite fine when downloading this in 2009-09-08 ~15:30 US Central Time).

PHP is by default NOT enabled; to enable uncomment one line in httpd.conf and restart server:

Default /etc/apache2/httpd.conf (== /private/etc/apache2/httpd.conf)

# 2008-02-27 Wed: removing preceeding '#' from line below 
LoadModule php5_module libexec/apache2/