The following notes are how I got Apache 2 and PHP 5 (or PHP 4) working together on Linux. These instructions also apply, mostly, for any UNIX-like system, especially other Linux distributions. If you have a recent Linux distribution (say since 2002), you already have Apache 2 and PHP, so you don't need to do this unless you want the latest Apache 2 or PHP release or need to customize the Apache or PHP software. Don't forget to remove (or at least disable) the Apache rpm package if you install your own custom Apache.

Apache 2 Version Tip: Beginning with Apache 2.0.42 the API will be kept stable (yeah!). That means you will NOT have to recompile modules (and possibly upgrade/fix source) every time you install a new Apache release. This assumes you stay in the same Apache release series. For example, upgrading from 2.2.0 to 2.2.2 should work. This will not apply to upgrading to the next series (e.g., "development" 2.3.x or "stable" 2.4.x).

I was only able to get PHP working with Apache 2 as a *.so DSO ("dynamic shared object"), as opposed to compiled into Apache (with a static *.a library). I think DSO is the only way PHP is supported now on Apache 2.

I first used httpd-2.0.43 and php-4.3.0 with RedHat 7.3. I am now using httpd-2.2.3 and php-5.2.0 with SUSE 10.1.

Note: If you have problems with PHP and think it's a recent bug, you may want to consider using the latest http://snaps.php.net/ snapshot. Beware that snapshots frequently have regression and are not for production use. Usually problems are because of mis-configuration, not bugs, so snapshots will probably hurt more than help.

1. In the Apache 2 source directory, create a Makefile by typing:

   ./configure --prefix=/usr/local/apache / --enable-so / --enable-cgi / --enable-info / --enable-rewrite / --enable-speling / --enable-usertrack / --enable-deflate / --enable-ssl / --enable-mime-magic

   You only need the enable-so line above. For information on other options, type ./configure --help and see "Compiling and Installing" in the Apache 2 Documentation, http://httpd.apache.org/ 
   
2. Make Apache from the just-created Makefile:

   make

3. If make is successful, install Apache as root:

   make install

4. Download/unpack PHP source from the PHP website, http://www.php.net/ 
   Pick the latest from the 4.x series or 5.x series. 
   
5. In the PHP source directory, create a Makefile by typing:

   ./configure / --with-apxs2=/usr/local/apache/bin/apxs / --with-mysql / --prefix=/usr/local/apache/php / --with-config-file-path=/usr/local/apache/php / --enable-force-cgi-redirect / --disable-cgi / --with-zlib / --with-gettext / --with-gdbm

   You only need the --with-apxs2, and prefix lines. --with-mysql adds MySql (you need to specify the directory if it's in a unusual location (e.g., --with-mysql=/usr/local ), --with-config-file moves the php.ini file location, disable-cgi disables the CGI version, which is not needed if you use Apache modules. It also enables and installs the command line interface (CLI) version. --with-zlib allows use of gzip-type compression, --with-gettext is for internationalization, and --with-gdbm allows access to GDBM databases. For more information, type ./configure --help and see the "Installation" chapter in the PHP Manual, http://ww.php.net/docs.php 
   
6. Make PHP from the just-created Makefile:

   make

7. If make is successful, type this as root to install PHP:

   make install

   If you are not root (I do not perform makes while root, for security and safety reasons), become root and type the following:

   make install-su

8. If file /usr/local/apache/modules/libphp5.so does not exist or is an older version, type this (change this to libphp4.so for PHP 4):

   cp -p .libs/libphp5.so /usr/local/apache/modules

9. Install the php.ini file:

   cp -p php.ini-recommended /usr/local/apache/php/php.ini

10. Add these directives are in /usr/local/apache/conf/httpd.conf (if already there, verify they are correct):

    # Make sure there's only **1** line for each of these 2 directives: # Use for PHP 4.x: #LoadModule php4_module modules/libphp4.so #AddHandler php-script php # Use for PHP 5.x: LoadModule php5_module modules/libphp5.so AddHandler php5-script php # Add index.php to your DirectoryIndex line: DirectoryIndex index.html index.php AddType text/html php # PHP Syntax Coloring # (optional but useful for reading PHP source for debugging): AddType application/x-httpd-php-source phps

    Note 1: The php documentation recommends AddType application/x-httpd-php php instead of the above. However, it causes problems with the "MultiViews" feature of HTTP. That is, if the .php extension is left off a URL, and with certain browser Accept headers, Apache will not know .php (application/x-httpd-php) is HTML and will return a 406 Not Acceptable error. Using the AddType and AddHandler as shown above fixes this problem. For details see Mark Tranchant's webpage, "Using Apache's MultiViews with PHP whilst avoid 406 errors," and PHP bug 28023.

    Note 2: PHP Syntax coloring isn't required, but it's very nice for looking at your php source while debugging. Here's an example.

    Note 3: just for completeness I'll mention that you should be able to use SetOutputFilter / SetInputFilter instead of AddType, but you can't use both. However, SetOutputFilter / SetInputFilter no longer works for me. It used to work with an earlier PHP 4.x or Apache 2 version, but not with Apache 2.0.47/PHP 4.3.3. I understand this (PHP as an Apache 2 filter) is experimental, so I don't use it anymore:

    <Files *.php> SetOutputFilter PHP SetInputFilter PHP </Files>

11. You're now ready to try it out. Start Apache (httpd) as root:

    /usr/local/apache/bin/apachectl start

12. Perform these sanity checks to verify your install went OK:

    $ /usr/local/apache/bin/httpd -t Syntax OK $ /usr/local/apache/bin/httpd -v Server version: Apache/2.2.2 Server built: May 29 2006 12:40:55 $ /usr/local/apache/bin/httpd -V Server version: Apache/2.2.2 Server built: May 29 2006 12:40:55 Server's Module Magic Number: 20051115:2 Server loaded: APR 1.2.7, APR-Util 1.2.7 Compiled using: APR 1.2.7, APR-Util 1.2.7 Architecture: 32-bit Server MPM: Prefork threaded: no forked: yes (variable process count) Server compiled with.... -D APACHE_MPM_DIR="server/mpm/prefork" -D APR_HAS_SENDFILE -D APR_HAS_MMAP -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled) -D APR_USE_SYSVSEM_SERIALIZE -D APR_USE_PTHREAD_SERIALIZE -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT -D APR_HAS_OTHER_CHILD -D AP_HAVE_RELIABLE_PIPED_LOGS -D DYNAMIC_MODULE_LIMIT=128 -D HTTPD_ROOT="/usr/local/apache" -D SUEXEC_BIN="/usr/local/apache/bin/suexec" -D DEFAULT_PIDLOG="logs/httpd.pid" -D DEFAULT_SCOREBOARD="logs/apache_runtime_status" -D DEFAULT_LOCKFILE="logs/accept.lock" -D DEFAULT_ERRORLOG="logs/error_log" -D AP_TYPES_CONFIG_FILE="conf/mime.types" -D SERVER_CONFIG_FILE="conf/httpd.conf" $ /usr/local/apache/bin/httpd -S VirtualHost configuration: . . . $ /usr/local/apache/bin/httpd -l Compiled in modules: core.c . . . mod_so.c $ /usr/local/apache/bin/httpd -M Loaded Modules: . . . php5_module (shared) Syntax OK (the above works for Apache 2.2.x and higher only) $ ps -ef |grep httpd root 24069 1 0 09:17 ? 00:00:08 /usr/local/apache/bin/httpd -k s apache 29917 24069 0 15:30 ? 00:00:00 /usr/local/apache/bin/httpd -k s . . .

    Note: on BSD-based UNIX systems, you need to use "ps -aux" instead of "ps -ef".

13. Access your webserver with telnet. Type HEAD / HTTP/1.0 followed by a blank line:

    $ telnet localhost 80 Trying 127.0.0.1... Connected to localhost (127.0.0.1). Escape character is '^]'. HEAD / HTTP/1.0 HTTP/1.1 200 OK Date: Mon, 29 May 2006 23:28:18 GMT Server: Apache/2.2.2 (Unix) mod_ssl/2.2.2 OpenSSL/0.9.7a PHP/5.1.4 X-Powered-By: PHP/5.1.4 Last-Modified: Wed, 15 Mar 2006 06:53:17 GMT Vary: Accept-Encoding Connection: close Content-Type: text/html; charset=ISO-8859-1 Content-Language: en Connection closed by foreign host.

14. Access your webserver with your favorite browser. The following is a good test page to use for PHP. You only need the one line in bold is needed to display PHP configuration information. Name the file anything you want, but it must end with .php, such as phpinfo.php, and move the file to your web server content directory (for me /usr/local/apache/htdocs), with read permission set:

    <html> <head> <title>PHP Test</title> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> </head> <body> <h1>PHP Test</h1> <p> <b>An Example of PHP in Action</b><br /> <?php echo "The Current Date and Time is: <br>"; echo date("g:i A l, F j Y.");?> </p> <h2>PHP Information</h2> <p> <?php phpinfo(); ?> </p> </body> </html>

    • Disabling Existing Apache Software

    If Apache is already installed with your Linux distribution you have to disable it before installing your own custom version. To do this, type the following under RedHat Linux:

    /sbin/chkconfig --del httpd /etc/init.d/httpd stop

    You may also remove the httpd and php rpm packages, and dependent packages, if you wish.

    • Automatic Startup of Apache

    To start Apache automatically, follow these steps:

    • Copy Apache startup file to the startup directory:

      cp /usr/local/apache/bin/apachectl /etc/init.d/

    • Edit /etc/init.d/apachectl by inserting these 2 lines in bold:

      #!/bin/sh # # chkconfig: - 85 15 # description: Apache is a Web server used to serve HTML files and CGI. # # Copyright 2000-2005 The Apache Software Foundation or its licensors, as # applicable. . . . # Apache control script designed to allow an easy command line interface # to controlling Apache. Written by Marc Slemko, 1997/08/23 . . .

    • Enable httpd to startup automatically:

      /sbin/chkconfig --add apachectl /sbin/chkconfig --level 2 apachectl on

      This works for RedHat Linux, Mandrake, SuSE, and Sun Java Desktop System. The equivalent of chkconfig for Debian is: 
      update-rc.d apachectl defaults 
      For other distributions, make appropriate softlinks to directories /etc/rc*.d/ 
      
    • Reboot Linux to verify Apache starts

    [Thanks to Beriah Dutcher and others]

    • Make doesn't make dynamic library libphp5.so, just static library libphp5.a

    First make sure libphp5.so isn't there. It's usually in the libs or .libs subdirectory. Run find from the PHP source directory root: find . -name libphp5.soIf that doesn't work, make sure you use the --with-apxs2 option with the correct directory in ./configure. For example: 
    ./configure --with-mysql --with-apxs2=/path/to/apache/apxs 
    When re-running ./configure always start with a fresh, clean source directory (no object).

    (For PHP 4, substitute libphp4.so and libphp4.a for libphp5.so and libphp5.a, respectively.)

    • PHP 5: My PHP scripts that worked with PHP 4 now ignores input variables

    If you have old PHP 4 scripts you don't want to convert to PHP 5, change this line in your php.ini file:

    register_long_arrays = On

    For the long term, you may want to upgrade your PHP software or convert the PHP source code to use new-style variables. E.g., use $_REQUEST[i] instead of $i

    • PHP 5.2.0 Upgrade from 5.1.x (November 2006)

    I had one problem with upgrading from PHP 5.1.x to 5.2.0. The Phorum 3 software I use has a function date_format that now conflicts with a new PHP 5.2 internal function, also called date_format. This new function is used for PHP 5.2.x's new "datetime support". I fixed this by renaming Phorum's date_formatfunction to not conflict with PHP's function. See also PHP 5.2 Update Info for more PHP 5.2 upgrade information.

    • PHP 5.x: you may need to upgrade libxml2 to use XML

    To use PHP 5 and XML (--with-xml), you need the libxml2 library version 2.6.0 or greater. You may need to upgrade if you have an older Linux distribution. Check with rpm -q libxml2 
    If it's not installed, check your installation disks for the libxml2 package. If it's too old, you can get the library from XMLSoft.org. You will probably need to compile and install it yourself.

    • PHP 4.3.5 / 4.3.6 / 5.0RC1 PCRE Regression (March 2004)

    If you use PHP 4.3.5, 4.3.6, or PHP 5.0 RC1 with PCRE (Perl Regular Expressions, the default), you get a core dump when you try and restart (SIGHUP) Apache (at least with Apache 2.0.49). The cause is from adding a new version of PCRE, 4.5, in PHP. This is fixed in PHP 4.3.7 and 5.0.

    The symptom are these messages in error_log (which is also a symptom for lots of other memory-type bugs in Apache):

    [Wed Mar 31 17:14:43 2004] [notice] SIGHUP received. Attempting to restart [Wed Mar 31 17:14:43 2004] [notice] seg fault or similar nasty error detected in the parent process [Wed Mar 31 17:14:48 2004] [warn] pid file /var/run/httpd.pid overwritten -- Unclean shutdown of previous Apache run?

    To fix, upgrade to PHP 4.3.7 or higher, which fixes it (PHP 5.0 or higher also fixes the bug). A workaround is to stop/start Apache, instead of restarting Apache. For details, see PHP bug 27810.

    • ServerRoot Installation Directory

    By default, Apache is installed in ServerRoot, as specified in httpd.conf or the httpd -d option: 
    ServerRoot "/usr/local/apache" 
    Some packagers and distributions move the location to /usr/local/httpd or /usr/local/apache2 so check that Apache is installed where you say it is, and check that you don't have two separate Apache installations by mistake.

    • PHP-required Apache files must be present

    PHP expects certain files to be present. They may be missing for some Linux distributions, which tend to separate files among the /var, /etc, and other directories. The apxs program expects to find httpd under the bin directory where apache is installed (by default /usr/local/apache/bin). PHP expects to find the os.h and unixd.h header files under the include directory where apache is installed (by default /usr/local/apache/include).

    • MySQL

    Use the --with-mysql configure option to build PHP with PHP's version of MySql. If you want the system's MySQL, or are also using MySql with another apache module (e.g., mod_perl), use this: with-mysql=/usr

    Make sure the MySQL developent headers are installed. This is usually package mysql-devel (thanks to Dev for the tip)

    • Custom OpenSSL and SSL

    When using "--enable-ssl" (i.e, build with OpenSSL), the configure script will try to guess the location of OpenSSL. If you're using your own custom SSL, you must specify the location. For example, "--with-ssl=/usr/local/ssl" (of course, you can use the SSL and PHP that comes with Redhat 9 and other distributions).

    Please note that mod_ssl is only for Apache 1.x. Apache 2.x does not use mod_ssl—SSL is built into Apache 2.x.

    Jason reports that with RedHat 9 on his system, the make failed at mod_ssl. It needed a missing krb5.h header file. The fix is to Add an environment variable, $CFLAGS, before making PHP. That is: 
    "-I/usr/kerberos/include/ -L/usr/kerberos/lib"

    • gdbm 
    If you get this error when using "--with-gdbm": 
    configure: error: DBA: Could not find necessary header file(s). 
    then you are probably missing the gdbm-devel rpm package.

    • Apache 1.x and Apache 2 Configuration Directives 
    The "AddModule," "AgentLog," "ReferrerLog," "RefererIgnore," "BindAddress," "ClearModuleList," "Port," "FancyIndexing," "ServerType," "AccessConfig," and "ResourceConfig" directives in Apache 1.x no longer exist in Apache 2. Also, "HAVE_*" httpd.conf definitions no longer exist. Comment them out of your httpd.conf for Apache 2. Most of these directives have been replaced by other directive(s).

    • Error after glibc library upgrade

    Apache should still work after upgrading glibc with security and bug fixes for the same release. If you use another architecture (say from or to i386/i686), you need to recompile. One symptom is an error like this in your Apache error_log: 
    [error] (38)Function not implemented:

    • make clean

    Kåre Olaussen adds this note: If you're compiling php4 for both Apache 1.3 and Apache 2, use a separate php source directory for each version of Apache. "The module wouldn't load into Apache 2, because I had forgotten to run make clean in between." [Ed. note: I recommend untaring the source from scratch in another directory, that way you are sure no old state information is left behind from previous makes. Do this for any configuration or version changes.]

    • Enabling register_globals for Apache 2

    From Duke: For those of you that are desperately trying to enable register_globals on a per-directory basis using Apache 2 with PHP 4 [or PHP 5] using.htaccess files, the syntax is different from Apache 1.x. In the directory you want to enable register_globals (or pretty much any other on/off setting), add an .htaccess file containing:

    php_value register_globals 1

    Note that php_flag does not work with Apache 2. Neither does on / off — you must use 0 (off) or 1 (on).

    [Editor's note: To enable globally, add register_globals=off to your php.ini file.]

    To enable register_globals on a per-directory basis, you can add to a <Directory> stanza or create a .htaccess configuration file in the directory. To use.htaccess, you must first enable it by adding AllowOverride All (or some combination of AllowOverride options within the correct <Directory> stanza. Also newer PHP software, such as SquirrelMail, no longer require register_globals to be enabled. Keeping register_globals disalbed makes the system much more secure (as it's harder to set internal php variables through submitting html forms). ]

    • Multi-Processing Module (MPM): don't use multi-threading MPMs

    MPMs is how Apache 2 handles multiple web server requests. That is, with multiple processes or multiple threads or some combination. For now, on Linux (and even UNIX) you should only use the (default) prefork module with PHP. This is specified at compile time. Other MPM modules (any involving threads) break PHP. This is partly because PHP uses a great number of external libraries, and many or most of them are not thread-safe or thread-aware. In any case, Linux 2.4 doesn't handle threads efficiently yet—multiple processes are better (this changes with Linux 2.6, or RedHat 9 with 2.6 threads backported to Linux 2.4).

    • API module structure `php5_module' in file . . . is garbled

    If you get a message like this: 
    

    httpd: Syntax error on line 195 of /usr/local/apache/conf/httpd.conf: API module structure `php5_module' in file /usr/local/apache/modules/libphp5.so is garbled - perhaps this is not an Apache module DSO

    it's because your version of PHP wasn't built for the version of Apache you are using (For PHP 4, substitute php4_module . . . libphp4.so). Recompile PHP in a "fresh" source directory (where you haven't built PHP before) and make sure --prefix, --with-config-file and --with-apxs2 points to the correct Apache directories you are using and the libphp4.so file has been copied to your /usr/local/apache/modules directory.

    • PATH_INFO

    Dan Fitzpatrick notes that he uses PATH_INFO for many PHP scripts like /index.php/go/do/something (where parameters are passed to PHP as "fake" subdirectories). He received a 404 Not Found errors with Apache 2 but not Apache 1.3.27. He had to add "AcceptPathInfo On" to file httpd.conf. For details, seehttp://httpd.apache.org/docs-2.2/mod/core.html#acceptpathinfo

    • Using <?   ?> style tags in addition to <?php   ?> style tags

    If you want to also use the old-style (or MS ASP-like) tags <? and ?> then add this line to your php.ini file. This is the default starting with PHP 5: 

    short_open_tag = On

    • GD library now built-in PHP

    PHP 4.3.0 has gd built-in, just pass --with-gd to PHP configure.

    • --with-apache

    If you don't have Apache source at the default directory at /usr/local/apache, then use --with-apache=DIR with PHP configure, where DIR is the root source directory, This tells PHP where to look for the Apache source.

    • Redhat 9 
    Apache 2 and PHP is built-in RedHat 9 (packages httpd 2.0.40, and php 4.2.2). Apache is mostly under /usr/lib/httpd and /usr/sbin/httpd. PHP is at/usr/lib/httpd/modules/libphp4.so For a complete file listing, type: rpm -ql httpd php

    For RedHat 9, PHP 4.3.1 gives a compiler errors with RedHat 9 similar to: my_malloc.c:24: undefined reference to `errno' 
    The problem is with mysql and will have to wait for a fix from them. Until then, add this line: 
    #include <errno.h> 
    to the beginning of file ./ext/mysql/libmysql/mysql.h in your PHP source and remake PHP (from scratch).

    • Notes about Gentoo Linux and Apache2 with PHP

    LoadModule php5_module modules/libphp5.so 
    becomes: 
    LoadModule php5_module /usr/lib/apache2-extramodules/libphp5.so

    To start automatically under Gentoo: 
    rc-update add apache2 default 
    (change php5 to php4 for PHP 4)

    [Thanks to Phillip Temple]