# Installation

This section holds common questions about the way to install PHP. PHP is available for almost any OS, and almost any web server.

To install PHP, follow the instructions in install.

Why shouldn't I use Apache2 with a threaded MPM in a production environment?

PHP is glue. It is the glue used to build cool web applications by sticking dozens of 3rd-party libraries together and making it all appear as one coherent entity through an intuitive and easy to learn language interface. The flexibility and power of PHP relies on the stability and robustness of the underlying platform. It needs a working OS, a working web server and working 3rd-party libraries to glue together. When any of these stop working PHP needs ways to identify the problems and fix them quickly. When you make the underlying framework more complex by not having completely separate execution threads, completely separate memory segments and a strong sandbox for each request to play in, further weaknesses are introduced into PHP's system.

If you want to use a threaded MPM, look at a FastCGI configuration where PHP is running in its own memory space.

Unix/Windows: Where should my &php.ini; file be located?

By default on Unix it should be in `/usr/local/lib` which is `<install-path>/lib`. Most people will want to change this at compile-time with the --with-config-file-path flag. You would, for example, set it with something like:

    --with-config-file-path=/etc

And then you would copy `php.ini-development` from the distribution to `/etc/php.ini` and edit it to make any local changes you want.

    --with-config-file-scan-dir=PATH

On Windows the default path for the &php.ini; file is the Windows directory. If you're using the Apache webserver, &php.ini; is first searched in the Apaches install directory, e.g. `c:\program files\apache group\apache`. This way you can have different &php.ini; files for different versions of Apache on the same machine.

See also the chapter about the configuration file.

Unix: I installed PHP, but every time I load a document, I get the message 'Document Contains No Data'! What's going on here?

This probably means that PHP is having some sort of problem and is core-dumping. Look in your server error log to see if this is the case, and then try to reproduce the problem with a small test case. If you know how to use 'gdb', it is very helpful when you can provide a backtrace with your bug report to help the developers pinpoint the problem. If you are using PHP as an Apache module try something like:

- Stop your httpd processes

- gdb httpd

- Stop your httpd processes

- > run -X -f /path/to/httpd.conf

- Then fetch the URL causing the problem with your browser

- > run -X -f /path/to/httpd.conf

- If you are getting a core dump, gdb should inform you of this now

- type: bt

- You should include your backtrace in your bug report. This should be submitted to &url.php.bugs;

If your script uses the regular expression functions (`preg_match` and friends), you should make sure that you compiled PHP and Apache with the same regular expression package. This should happen automatically with PHP and Apache 1.3.x

Unix: I installed PHP using RPMS, but Apache isn't processing the PHP pages! What's going on here?

Assuming you installed both Apache and PHP from RPM packages, you need to uncomment or add some or all of the following lines in your &httpd.conf; file:

    # Extra Modules
    AddModule mod_php.c
    AddModule mod_perl.c

    # Extra Modules
    LoadModule php_module         modules/mod_php.so
    LoadModule php5_module        modules/libphp5.so
    LoadModule perl_module        modules/libperl.so

And add:

    AddType application/x-httpd-php .php

... to the global properties, or to the properties of the VirtualDomain you want to have PHP support added to.

Unix: I patched Apache with the FrontPage extensions patch, and suddenly PHP stopped working. Is PHP incompatible with the Apache FrontPage extensions?

No, PHP works fine with the FrontPage extensions. The problem is that the FrontPage patch modifies several Apache structures, that PHP relies on. Recompiling PHP (using 'make clean ; make') after the FP patch is applied would solve the problem.

Unix/Windows: I have installed PHP, but when I try to access a PHP script file via my browser, I get a blank screen.

Do a 'view source' in the web browser and you will probably find that you can see the source code of your PHP script. This means that the web server did not send the script to PHP for interpretation. Something is wrong with the server configuration - double check the server configuration against the PHP installation instructions.

Unix/Windows: I have installed PHP, but when try to access a PHP script file via my browser, I get a server 500 error.

Something went wrong when the server tried to run PHP. To get to see a sensible error message, from the command line, change to the directory containing the PHP executable (`php.exe` on Windows) and run `php -i`. If PHP has any problems running, then a suitable error message will be displayed which will give you a clue as to what needs to be done next. If you get a screen full of HTML codes (the output of the `phpinfo` function) then PHP is working, and your problem may be related to your server configuration which you should double check.

Some operating systems: I have installed PHP without errors, but when I try to start Apache I get undefined symbol errors:

    [mybox:user /src/php5] root# apachectl configtest
     apachectl: /usr/local/apache/bin/httpd Undefined symbols:
      _compress
      _uncompress

This has actually nothing to do with PHP, but with the MySQL client libraries. Some need `--with-zlib`, others do not. This is also covered in the MySQL FAQ.

Windows: I have installed PHP, but when I try to access a PHP script file via my browser, I get the error:

    cgi error:
     The specified CGI application misbehaved by not
     returning a complete set of HTTP headers.
     The headers it did return are:

This error message means that PHP failed to output anything at all. To get to see a sensible error message, from the command line, change to the directory containing the PHP executable (`php.exe` on Windows) and run `php -i`. If PHP has any problems running, then a suitable error message will be displayed which will give you a clue as to what needs to be done next. If you get a screen full of HTML codes (the output of the `phpinfo` function) then PHP is working.

Once PHP is working at the command line, try accessing the script via the browser again. If it still fails then it could be one of the following:

- File permissions on your PHP script, `php.exe`, `php5ts.dll`, &php.ini; or any PHP extensions you are trying to load are such that the anonymous internet user `ISUR_<machinename>` cannot access them.

- The script file does not exist (or possibly isn't where you think it is relative to your web root directory). Note that for IIS you can trap this error by ticking the 'check file exists' box when setting up the script mappings in the Internet Services Manager. If a script file does not exist then the server will return a 404 error instead. There is also the additional benefit that IIS will do any authentication required for you based on the NTLanMan permissions on your script file.

Windows: I've followed all the instructions, but still can't get PHP and IIS to work together!

Make sure any user who needs to run a PHP script has the rights to run `php.exe`! IIS uses an anonymous user which is added at the time IIS is installed. This user needs rights to `php.exe`. Also, any authenticated user will also need rights to execute `php.exe`. And for IIS4 you need to tell it that PHP is a script engine. Also, you will want to read this faq.

When running PHP as CGI with IIS, PWS, OmniHTTPD or Xitami, I get the following error: `Security Alert! PHP CGI cannot be accessed directly.`.

You must set the cgi.force_redirect directive to `0`. It defaults to `1` so be sure the directive isn't commented out (with a `;`). Like all directives, this is set in &php.ini;

Because the default is `1`, it's critical that you're 100% sure that the correct &php.ini; file is being read. Read this faq for details.

How do I know if my &php.ini; is being found and read? It seems like it isn't as my changes aren't being implemented.

To be sure your &php.ini; is being read by PHP, make a call to `phpinfo`. Near the top, there will be a listing called `Configuration File (php.ini)`. This will tell you where PHP is looking for &php.ini; and whether or not it's being read. If just a directory `PATH` exists, then it's not being read, and you should put your &php.ini; in that directory. If &php.ini; is included within the `PATH`, it is being read.

If &php.ini; is being read and you're running PHP as a module, then be sure to restart your web server after making changes to &php.ini;

See also `php_ini_loaded_file`.

How do I add my PHP directory to the `PATH` on Windows?

On Windows:

- Go to Control Panel and open the System icon (Start → Control Panel)

- Go to the Advanced tab

- Click on the 'Environment Variables' button

- Look into the 'System Variables' pane

- Find the Path entry (you may need to scroll to find it)

- Double click on the Path entry

- Enter your PHP directory at the end, including ';' before (e.g. `;C:\php`)

- Press OK

Be sure to reboot after following the steps above to ensure that the `PATH` changes are applied.

How do I make the &php.ini; file available to PHP on Windows?

There are several ways of doing this. If you are using Apache, refer to the Apache documentation, otherwise you must set the `PHPRC` environment variable.

Windows: How do I verify that PHP can write to the temporary directory under IIS?

1. Right-click the temporary directory (`%TEMP%`) in File Explorer to get the permissions. The temporary directory is available from the configuration or `phpinfo`.

2. For IIS, check that user `IIS_User` has `MODIFY` permission.

Is it possible to use Apache content negotiation (MultiViews option) with PHP?

If links to PHP files include extension, everything works perfect. This FAQ is only for the case when links to PHP files don't include extension and you want to use content negotiation to choose PHP files from URL with no extension. In this case, replace the line `AddType application/x-httpd-php .php` with:

    AddHandler php5-script php
    AddType text/html php

This solution doesn't work for Apache 1 as PHP module doesn't catch `php-script`.

Is PHP limited to process GET and POST request methods only?

No, it is possible to handle any request method, e.g. CONNECT. Proper response status can be sent with `header`. If only GET and POST methods should be handled, it can be achieved with this Apache configuration:

    <LimitExcept GET POST>
    Deny from all
    </LimitExcept>