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# Chapter 53. Installation FAQ

This section holds common questions about the way to install PHP. PHP is available for almost any OS (except maybe for MacOS before OSX), and almost any web server.

To install PHP, follow the instructions in Part II in PHP Manual.

1. Why shouldn't I use Apache2 with a threaded MPM in a production environment?
2. Unix/Windows: Where should my `php.ini` file be located?
3. Unix: I installed PHP, but every time I load a document, I get the message 'Document Contains No Data'! What's going on here?
4. Unix: I installed PHP using RPMS, but Apache isn't processing the PHP pages! What's going on here?
5. Unix: I installed PHP 3 using RPMS, but it doesn't compile with the database support I need! What's going on here?
6. Unix: I patched Apache with the FrontPage extensions patch, and suddenly PHP stopped working. Is PHP incompatible with the Apache FrontPage extensions?
7. Unix/Windows: I have installed PHP, but when I try to access a PHP script file via my browser, I get a blank screen.
8. Unix/Windows: I have installed PHP, but when try to access a PHP script file via my browser, I get a server 500 error.
9. Some operating systems: I have installed PHP without errors, but when I try to start apache I get undefined symbol errors:

    [mybox:user /src/php4] root# apachectl configtest
     apachectl: /usr/local/apache/bin/httpd Undefined symbols:
      _compress
      _uncompress

10. Windows: I have installed PHP, but when I 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:

11. Windows: I've followed all the instructions, but still can't get PHP and IIS to work together!
12. When running PHP as CGI with IIS, PWS, OmniHTTPD or Xitami, I get the following error: Security Alert! PHP CGI cannot be accessed directly..
13. 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.
14. How do I add my PHP directory to the PATH on Windows?
15. How do I make the `php.ini` file available to PHP on windows?
16. Is it possible to use Apache content negotiation (MultiViews option) with PHP?
17. Is PHP limited to process GET and POST request methods only?

1. 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, feet of clay are introduced into PHP's system.

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

And finally, this warning against using a threaded MPM is not as strong for Windows systems because most libraries on that platform tend to be threadsafe.

2. 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-dist` 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.

3. 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 http://bugs.php.net/

If your script uses the regular expression functions (ereg() 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

4. 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_php3.c
    AddModule mod_perl.c

    # Extra Modules
    LoadModule php_module         modules/mod_php.so
    LoadModule php3_module        modules/libphp3.so     # for PHP 3
    LoadModule php4_module        modules/libphp4.so     # for PHP 4
    LoadModule perl_module        modules/libperl.so

And add:

    AddType application/x-httpd-php3 .php3    # for PHP 3
    AddType application/x-httpd-php .php      # for PHP 4

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

5. Unix: I installed PHP 3 using RPMS, but it doesn't compile with the database support I need! What's going on here?

Due to the way PHP 3 built, it is not easy to build a complete flexible PHP RPM. This issue is addressed in PHP 4. For PHP 3, we currently suggest you use the mechanism described in the INSTALL.REDHAT file in the PHP distribution. If you insist on using an RPM version of PHP 3, read on...

The RPM packagers are setting up the RPMS to install without database support to simplify installations and because RPMS use /usr/ instead of the standard /usr/local/ directory for files. You need to tell the RPM spec file which databases to support and the location of the top-level of your database server.

This example will explain the process of adding support for the popular MySQL database server, using the mod installation for Apache.

Of course all of this information can be adjusted for any database server that PHP supports. We will assume you installed MySQL and Apache completely with RPMS for this example as well.

- First remove mod_php3 :

      rpm -e mod_php3

- Then get the source rpm and INSTALL it, NOT --rebuild

      rpm -Uvh mod_php3-3.0.5-2.src.rpm

- Then edit the `/usr/src/redhat/SPECS/mod_php3.spec` file

  In the %build section add the database support you want, and the path.

  For MySQL you would add --with-mysql=/usr The %build section will look something like this:

      ./configure --prefix=/usr \
      --with-apxs=/usr/sbin/apxs \
      --with-config-file-path=/usr/lib \
      --enable-debug=no \
      --enable-safe-mode \
      --with-exec-dir=/usr/bin \
      --with-mysql=/usr \
      --with-system-regex

- Once this modification is made then build the binary rpm as follows:

      rpm -bb /usr/src/redhat/SPECS/mod_php3.spec

- Then install the rpm

      rpm -ivh /usr/src/redhat/RPMS/i386/mod_php3-3.0.5-2.i386.rpm

Make sure you restart Apache, and you now have PHP 3 with MySQL support using RPM's. Note that it is probably much easier to just build from the distribution tarball of PHP 3 and follow the instructions in `INSTALL.REDHAT` found in that distribution.

6. 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.

7. 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.

8. 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.

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

    [mybox:user /src/php4] 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.

10. Windows: I have installed PHP, but when I 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`, `php4ts.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.

11. 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.

12. 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.

13. 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() and near the top 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 than it's not being read and you should put your `php.ini` in that directory. If `php.ini` is included within the PATH than 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`

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

On Windows NT, 2000, XP and 2003:

- Go to Control Panel and open the System icon (Start -> Settings -> Control Panel -> System, or just Start -> Control Panel -> System for Windows XP/2003)

- 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 ant the end, including ';' before (e.g. ;C:\php)

- Press OK and restart your computer

On Windows 98/Me you need to edit the `autoexec.bat` file:

- Open the Notepad (Start -> Run and enter notepad)

- Open the `C:\autoexec.bat` file

- Locate the line with PATH=C:\WINDOWS;C:\WINDOWS\COMMAND;..... and add: ;C:\php to the end of the line

- Save the file and restart your computer

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

The PHP manual used to promote the copying of files into the Windows system directory, this is because this directory (`C:\Windows`, `C:\WINNT`, etc.) is by default in the systems PATH. Copying files into the Windows system directory has long since been deprecated and may cause problems.

15. 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, read their installation specific instructions (Apache 1, Apache 2), otherwise you must set the PHPRC environment variable:

On Windows NT, 2000, XP and 2003:

- Go to Control Panel and open the System icon (Start -> Settings -> Control Panel -> System, or just Start -> Control Panel -> System for Windows XP/2003)

- Go to the Advanced tab

- Click on the 'Environment Variables' button

- Look into the 'System variables' pane

- Click on 'New' and enter 'PHPRC' as the variable name and the directory where `php.ini` is located as the variable value (e.g. C:\php)

- Press OK and restart your computer

On Windows 98/Me you need to edit the `autoexec.bat` file:

- Open the Notepad (Start -> Run and enter notepad)

- Open the `C:\autoexec.bat` file

- Add a new line to the end of the file: set PHPRC=C:\php (replace C:\php with the directory where `php.ini` is located). Please note that the path cannot contain spaces. For instance, if you have installed PHP in `C:\Program Files\PHP`, you would enter `C:\PROGRA~1\PHP` instead.

- Save the file and restart your computer

16. 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:

    # PHP 4
    AddHandler php-script php
    AddType text/html php

    # PHP 5
    AddHandler php5-script php
    AddType text/html php

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

17. 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>

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