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Editing wp-config.php

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One of the most important files in your WordPress installation is the wp-config.php file. This file is located in the root of your WordPress file directory and contains your website's base configuration details, such as database connection information.

When you first download WordPress, the wp-config.php file isn’t included. The WordPress setup process will create a wp-config.php file for you based on the information you provide.

Advanced users can manually create a wp-config.php file by locating the sample file named "wp-config-sample.php" (located in the root install-directory), editing it as required, and then saving it as wp-config.php.

NOTE: The contents of the wp-config-sample.php file are in a very specific order. The order matters. If you already have a wp-config.php file, rearranging the contents of the file may create errors on your blog.

To change the wp-config.php file for your installation, you will need this information:

Database Name 
Database Name used by WordPress
Database Username 
Username used to access Database
Database Password 
Password used by Username to access Database
Database Host 
The hostname of your Database Server. A port number, Unix socket file path or pipe may be needed as well.

If your hosting provider installed WordPress for you, get the information from them. If you manage your own web server or hosting account, you will have this information as a result of creating the database and user.

Configure Database Settings

Important: never use a word processor like Microsoft Word for editing WordPress files!

Locate the file wp-config-sample.php in the base directory of your WordPress directory and open in a text editor.

NOTE: Since Version 2.6, wp-config.php can be moved to the directory directly above the WordPress application directory.


Default wp-config-sample.php

NOTE: This is an example of a default wp-config-sample.php. The values here are examples to show you what to do. Do not change these details here by editing this page, change them on your web server. If you make changes here by using the edit button, they will not work and you will be showing your password details to the world.
// ** MySQL settings - You can get this info from your web host ** //
/** The name of the database for WordPress */
define( 'DB_NAME', 'database_name_here' );

/** MySQL database username */
define( 'DB_USER', 'username_here' );

/** MySQL database password */
define( 'DB_PASSWORD', 'password_here' );

/** MySQL hostname */
define( 'DB_HOST', 'localhost' );
NOTE: Text inside /* */ are comments, for information purposes only.

Set Database Name

Replace 'database_name_here', with the name of your database, e.g. MyDatabaseName.

define( 'DB_NAME', 'MyDatabaseName' ); // Example MySQL database name

Set Database User

Replace 'username_here', with the name of your username e.g. MyUserName.

define( 'DB_USER', 'MyUserName' ); // Example MySQL username

Set Database Password

Replace 'password_here', with the your password, e.g. MyPassWord.

define( 'DB_PASSWORD', 'MyPassWord' ); // Example MySQL password

Set Database Host

Replace 'localhost', with the name of your database host, e.g. MyDatabaseHost. A port number or Unix socket file path may be needed as well.

define( 'DB_HOST', 'MyDatabaseHost' ); // Example MySQL Database host
NOTE: There is a good chance you will NOT have to change it. If you are unsure, try installing with the default value of 'localhost' and see if it works. If the install fails, contact your web hosting provider.
Possible DB_HOST values

Different hosting companies use different network settings for their mysql databases. If your hosting company is listed below in the left column, the value on the right is similar to the correct value for DB_HOST. Contact your tech support and/or search your hosting companies online Documentation to be sure.

Hosting Company DB_HOST Value Guess
1and1 db12345678
AN Hosting localhost
Aruba.it localhost or real IP provided with activation mail.
A Small Orange localhost
BlueHost localhost
DreamHost mysql.example.com
GoDaddy - Shared and 4GH Hosting In the Databases menu go to MySQL. To the right of the database name click on Actions and Details. The hostname is at the bottom of the window.
GoDaddy - cPanel Hosting localhost
GoDaddy - Plesk Hosting Use the IP address shown in the Databases Section in Plesk. Do not include :3306
HostGator localhost
HostICan localhost
ICDSoft localhost:/tmp/mysql5.sock
Infomaniak Network mysql.yourdomain
InMotion Hosting localhost
iPage username.ipagemysql.com
IPower username.ipowermysql.com
LaughingSquid localhost
MediaTemple Grid internal-db.s00000.gridserver.com - (Replace "00000" with the actual site number)
MediaTemple DV localhost
MegnaHost localhost
NearlyFreeSpeech.Net username.db
NetworkSolutions mysqlv5
one.com example.com.mysql
pair Networks dbnnnx.pair.com
QTH.com localhost
Rackspace Cloud localhost for unmanaged servers, variable for Cloud Sites like mysqlXY-AB.wcN.dfQ.stabletransit.com where X,Y,A,B,N,Q are variables
SysFix.eu Power Hosting datapower.sysfix.eu
Yahoo mysql
Hosts with cPanel localhost
Hosts with Plesk localhost
Hosts with DirectAdmin localhost
Tophost.it sql.your-domain-name.it



MySQL Alternate Port

If your host uses an alternate port number for your database you'll need to change the DB_HOST value in the wp-config.php file to reflect the alternate port provided by your host.

For localhost

define( 'DB_HOST', 'localhost:3307' );

Other

define( 'DB_HOST', 'mysql.example.com:3307' );

Replace 3307 with whatever port number your host gives you.

MySQL Sockets or Pipes

If your host uses Unix sockets or pipes, adjust the DB_HOST value in the wp-config.php file accordingly.

define( 'DB_HOST', 'localhost:/var/run/mysqld/mysqld.sock' );

Replace /var/run/mysqld/mysqld.sock with the socket or pipe information provided by your host.

Database character set

As of WordPress Version 2.2, DB_CHARSET was made available to allow designation of the database character set (e.g. tis620 for TIS620 Thai) to be used when defining the MySQL database tables.

The default value of utf8 (Unicode UTF-8) is almost always the best option. UTF-8 supports any language, so you typically want to leave DB_CHARSET at utf8 and use the DB_COLLATE value for your language instead.

This example shows utf8 which is considered the WordPress default value:

define( 'DB_CHARSET', 'utf8' );
WARNING: Those performing new installations

There usuallly should be no reason to change the default value of DB_CHARSET. If your blog needs a different character set, please read Character Sets and Collations MySQL Supports for valid DB_CHARSET values.

WARNING: Those performing upgrades (especially blogs that existed before 2.2)

If DB_CHARSET and DB_COLLATE do not exist in your wp-config.php file, DO NOT add either definition to your wp-config.php file unless you read and understand Converting Database Character Sets. Adding DB_CHARSET and DB_COLLATE to the wp-config.php file, for an existing blog, can cause major problems.

Database collation

As of WordPress Version 2.2, DB_COLLATE was made available to allow designation of the database collation (i.e. the sort order of the character set). In most cases, this value should be left blank (null) so the database collation will be automatically assigned by MySQL based on the database character set specified by DB_CHARSET. Set DB_COLLATE to one of the UTF-8 values defined in UTF-8 character sets for most Western European languages.

The WordPress default DB_COLLATE value:

define( 'DB_COLLATE', '' );

UTF-8 Unicode General collation

define( 'DB_COLLATE', 'utf8_general_ci' );

UTF-8 Unicode Turkish collation

define( 'DB_COLLATE', 'utf8_turkish_ci' );
WARNING: Those performing new installations

There usually should be no reason to change the default value of DB_COLLATE. Leaving the value blank (null) will insure the collation is automatically assigned by MySQL when the database tables are created.

WARNING: Those performing upgrades (especially blogs that existed before 2.2)

If DB_COLLATE and DB_CHARSET do not exist in your wp-config.php file, DO NOT add either definition to your wp-config.php file unless you read and understand Converting Database Character Sets. And you may be in need of a WordPress upgrade.


Security Keys

In Version 2.6, three (3) security keys, AUTH_KEY, SECURE_AUTH_KEY, and LOGGED_IN_KEY, were added to ensure better encryption of information stored in the user's cookies. (These collectively replaced a single key introduced in Version 2.5.) In Version 2.7 a fourth key, NONCE_KEY, was added to this group. When each key was added, corresponding salts were added: AUTH_SALT, SECURE_AUTH_SALT, LOGGED_IN_SALT, and NONCE_SALT.

You don't have to remember the keys, just make them long, random and complicated -- or better yet, use the the online generator. You can change these at any point in time to invalidate all existing cookies. This does mean that all users will have to login again.

Example (don't use these!):

define( 'AUTH_KEY',         't`DK%X:>xy|e-Z(BXb/f(Ur`8#~UzUQG-^_Cs_GHs5U-&Wb?pgn^p8(2@}IcnCa|' );
define( 'SECURE_AUTH_KEY',  'D&ovlU#|CvJ##uNq}bel+^MFtT&.b9{UvR]g%ixsXhGlRJ7q!h}XWdEC[BOKXssj' );
define( 'LOGGED_IN_KEY',    'MGKi8Br(&{H*~&0s;{k0<S(O:+f#WM+q|npJ-+P;RDKT:~jrmgj#/-,[hOBk!ry^' );
define( 'NONCE_KEY',        'FIsAsXJKL5ZlQo)iD-pt??eUbdc{_Cn<4!d~yqz))&B D?AwK%)+)F2aNwI|siOe' );
define( 'AUTH_SALT',        '7T-!^i!0,w)L#JK@pc2{8XE[DenYI^BVf{L:jvF,hf}zBf883td6D;Vcy8,S)-&G' );
define( 'SECURE_AUTH_SALT', 'I6`V|mDZq21-J|ihb u^q0F }F_NUcy`l,=obGtq*p#Ybe4a31R,r=|n#=]@]c #' );
define( 'LOGGED_IN_SALT',   'w<$4c$Hmd%/*]`Oom>(hdXW|0M=X={we6;Mpvtg+V.o<$|#_}qG(GaVDEsn,~*4i' );
define( 'NONCE_SALT',       'a|#h{c5|P &xWs4IZ20c2&%4!c(/uG}W:mAvy<I44`jAbup]t=]V<`}.py(wTP%%' );

A secret key makes your site harder to hack and access harder to crack by adding random elements to the password.

In simple terms, a secret key is a password with elements that make it harder to generate enough options to break through your security barriers. A password like "password" or "test" is simple and easily broken. A random, unpredictable password such as "88a7da62429ba6ad3cb3c76a09641fc" takes years to come up with the right combination. A 'salt is used to further enhance the security of the generated result.

The four keys are required for the enhanced security. The four salts are recommended, but are not required, because WordPress will generate salts for you if none are provided. They are included in wp-config.php by default for inclusiveness.

For more information on the technical background and breakdown of secret keys and secure passwords, see:

Advanced Options

The following sections may contain advanced / unsupported information, so please make sure you practice regular backups and know how to restore them before experimenting on a production installation.

table_prefix

The $table_prefix is the value placed in the front of your database tables. Change the value if you want to use something other than wp_ for your database prefix. Typically this is changed if you are installing multiple WordPress blogs in the same database.

// You can have multiple installations in one database if you give each a unique prefix.
$table_prefix = 'r235_'; // Only numbers, letters, and underscores please!

A second blog installation using the same database can be achieved simply by using a different prefix than your other installations.

$table_prefix = 'y77_'; // Only numbers, letters, and underscores please!

WordPress address (URL)

WP_SITEURL, defined since WordPress Version 2.2, allows the WordPress address (URL) to be defined. The value defined is the address where your WordPress core files reside. It should include the http:// part too. Do not put a slash "/" at the end. Setting this value in wp-config.php overrides the wp_options table value for siteurl and overrides the WordPress address (URL) field in the Administration > Settings > General panel when logging in using wp-login.php. It will _not_ update your Home url. Read more about this in depth in the link provided in the Note field:

NOTE: It won't change the Database value though, and the url will revert to the old database value if this line is removed from wp-config. Use the RELOCATE constant to change the siteurl value in the database.

If WordPress is installed into a directory called "wordpress" for the domain example.com, define WP_SITEURL like this:

define( 'WP_SITEURL', 'http://example.com/wordpress' );

Dynamically set WP_SITEURL based on $_SERVER['HTTP_HOST']

define( 'WP_SITEURL', 'http://' . $_SERVER['HTTP_HOST'] . '/path/to/wordpress' );
NOTE: A safer alternative for some installations would be to use the server-generated SERVER_NAME instead of the php/user-generated HTTP_HOST which is created dynamically by php based on the value of the HTTP HOST Header in the request, thus possibly allowing for file inclusion vulnerabilities. SERVER_NAME is set by the server configuration and is static.

Dynamically set WP_SITEURL based on $_SERVER['SERVER_NAME']

define( 'WP_SITEURL', 'http://' . $_SERVER['SERVER_NAME'] . '/path/to/wordpress' );

Blog address (URL)

WP_HOME is another wp-config.php option added in WordPress Version 2.2. Similar to WP_SITEURL, WP_HOME overrides the wp_options table value for home but does not change it permanently. home is the address you want people to type in their browser to reach your WordPress blog. It should include the http:// part and should not have a slash "/" at the end.

define( 'WP_HOME', 'http://example.com/wordpress' );

If you are using the technique described in Giving WordPress Its Own Directory then follow the example below. Remember, you will also be placing an index.php in your web-root directory if you use a setting like this.

define( 'WP_HOME', 'http://example.com' );

Dynamically set WP_HOME based on $_SERVER['HTTP_HOST']

define( 'WP_HOME', 'http://' . $_SERVER['HTTP_HOST'] . '/path/to/wordpress' );

Moving wp-content folder

Since Version 2.6, you can move the wp-content directory, which holds your themes, plugins, and uploads, outside of the WordPress application directory.

Set WP_CONTENT_DIR to the full local path of this directory (no trailing slash), e.g.

define( 'WP_CONTENT_DIR', dirname(__FILE__) . '/blog/wp-content' );

Set WP_CONTENT_URL to the full URI of this directory (no trailing slash), e.g.

define( 'WP_CONTENT_URL', 'http://example/blog/wp-content' );

Moving plugin folder

Set WP_PLUGIN_DIR to the full local path of this directory (no trailing slash), e.g.

define( 'WP_PLUGIN_DIR', dirname(__FILE__) . '/blog/wp-content/plugins' );

Set WP_PLUGIN_URL to the full URI of this directory (no trailing slash), e.g.

define( 'WP_PLUGIN_URL', 'http://example/blog/wp-content/plugins' );

If you have compability issues with plugins Set PLUGINDIR to the full local path of this directory (no trailing slash), e.g.

define( 'PLUGINDIR', dirname(__FILE__) . '/blog/wp-content/plugins' );

Moving themes folder

Unfortunately, you can not directly move the themes folder because its path is hardcoded relatively to the wp-content folder as:

$theme_root = WP_CONTENT_DIR . '/themes'; 

You may register additional theme directories using register_theme_directory.

See how to move the wp-content folder. For more details how the themes folder is determined, see wp-includes/theme.php.

Moving uploads folder

Set UPLOADS to :

define( 'UPLOADS', '/blog/wp-content/uploads' );

This path can not be absolute. It is always relative to ABSPATH

Modify AutoSave Interval

When editing a post, WordPress uses Ajax to auto-save revisions to the post as you edit. You may want to increase this setting for longer delays in between auto-saves, or decrease the setting to make sure you never lose changes. The default is 60 seconds.

define( 'AUTOSAVE_INTERVAL', 160 ); // Seconds

Post Revisions

WordPress, by default, will save copies of each edit made to a post or page, allowing the possibility of reverting to a previous version of that post or page. The saving of revisions can be disabled, or a maximum number of revisions per post or page can be specified.

Disable Post Revisions

If you do not set this value, WordPress defaults WP_POST_REVISIONS to true (enable post revisions). If you want to disable the awesome revisions feature, use this setting:

define( 'WP_POST_REVISIONS', false );

Note: Some users could not get this to function until moving the command to the first line under the initial block comment in config.php.

Specify the Number of Post Revisions

If you want to specify a maximum number of revisions, change false to an integer/number (e.g., 3 or 5).

define( 'WP_POST_REVISIONS', 3 );

Note: Some users could not get this to function until moving the command to the first line under the initial block comment in config.php.

Set Cookie Domain

The domain set in the cookies for WordPress can be specified for those with unusual domain setups. One reason is if subdomains are used to serve static content. To prevent WordPress cookies from being sent with each request to static content on your subdomain you can set the cookie domain to your non-static domain only.

define( 'COOKIE_DOMAIN', 'www.askapache.com' );

Enable Multisite / Network Ability

WP_ALLOW_MULTISITE is a feature introduced in WordPress Version 3.0 to enable multisite functionality previously achieved through WordPress MU. If this setting is absent from wp-config.php it defaults to false.

define( 'WP_ALLOW_MULTISITE', true );

Redirect Nonexistent Blogs

NOBLOGREDIRECT can be used to redirect the browser if the visitor tries to access a nonexistent blog.
E.g., http://nonexistent.example.com or http://example.com/nonexistent/.

define( 'NOBLOGREDIRECT', 'http://example.com' );

Debug

The WP_DEBUG option, added in WordPress Version 2.3.1, controls the reporting of some errors and warnings and enables use of the WP_DEBUG_DISPLAY and WP_DEBUG_LOG settings. The default value is false.

NOTE: The true and false values in the example are not set in apostrophes (') because they are boolean values.
define( 'WP_DEBUG', true );
define( 'WP_DEBUG', false );

Additionally, if you are planning on modifying some of WordPress' built-in JavaScript or Cascading Style Sheets, you should add the following code to your config file:

define( 'SCRIPT_DEBUG', true );

Then the uncompressed versions of scripts and stylesheets in wp-includes/js, wp-includes/css, wp-admin/js, and wp-admin/css will be loaded instead of the .min.css and .min.js versions.

In WordPress versions since 2.3.2, database errors are printed only if WP_DEBUG is set to true. In earlier versions, database errors were always printed. (Database errors are handled by the wpdb class and are not affected by PHP's error settings.)

In WordPress version 2.5, setting WP_DEBUG to true also raises the error reporting level to E_ALL and activates warnings when deprecated functions or files are used; otherwise, WordPress sets the error reporting level to E_ALL ^ E_NOTICE ^ E_USER_NOTICE.

Disable Javascript Concatenation

To result in a faster administration area, all Javascript files are concatenated into one URL. If Javascript is failing to work in your administration area, you can try disabling this feature:

define( 'CONCATENATE_SCRIPTS', false );

Configure Error Logging

Configuring error logging can be a bit tricky. First of all, default PHP error log and display settings are set in the php.ini file, which you may or may not have access to. If you do, they should be set to the desired settings for live PHP pages served to the public. It's strongly recommended that no error messages are displayed to the public and instead routed to an error log. Further more, error logs should not be located in the publicly accessible portion of your server. Sample recommended php.ini error settings:

error_reporting = 4339
display_errors = Off
display_startup_errors = Off
log_errors = On
error_log = /home/example.com/logs/php_error.log
log_errors_max_len = 1024
ignore_repeated_errors = On
ignore_repeated_source = Off
html_errors = Off

About Error Reporting 4339

This is a custom value that only logs issues that affect the functioning of your site, and ignores things like notices that may not even be errors. See PHP Error Constants for the meaning of each binary position for 1000011110011, which is the binary number equal to 4339. The far left 1 means report any E_RECOVERABLE_ERROR. The next 0 means do not report E_STRICT, (which is thrown when sloppy but functional coding is used) and so on. Feel free to determine your own custom error reporting number to use in place of 4339.

Obviously, you will want different settings for your development environment. If your staging copy is on the same server, or you don't have access to php.ini, you will need to override the default settings at run time. It's a matter of personal preference whether you prefer errors to go to a log file, or you prefer to be notified immediately of any error, or perhaps both. Here's an example that reports all errors immediately that you could insert into your wp-config.php file:

@ini_set( 'log_errors', 'Off' );
@ini_set( 'display_errors', 'On' );
@ini_set( 'error_reporting', E_ALL );
define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', false );
define( 'WP_DEBUG_DISPLAY', true );

Because wp-config.php is loaded for every page view not loaded from a cache file, it is an excellent location to set php ini settings that control your php installation. This is useful if you don't have access to a php.ini file, or if you just want to change some settings on the fly.

If you turn on error logging, remember to delete the file afterwards, as it will often be in a publicly accessible location, where anyone could gain access to your log.

Here is an example that turns php error_logging on and logs them to a specific file. If WP_DEBUG is defined to true, the errors will also be saved to this file. Just place this above any require_once or include commands.

@ini_set( 'log_errors', 'On' );
@ini_set( 'display_errors', 'Off' );
@ini_set( 'error_log', '/home/example.com/logs/php_error.log' );
/* That's all, stop editing! Happy blogging. */

Another example of logging errors, as suggested by Mike Little on the wp-hackers email list:

/**
 * This will log all errors notices and warnings to a file called debug.log in
 * wp-content (if Apache does not have write permission, you may need to create
 * the file first and set the appropriate permissions (i.e. use 666) )
 */
define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );
@ini_set( 'display_errors', 0 );

A refined version from Mike Little on the Manchester WordPress User Group:

/**
 * This will log all errors notices and warnings to a file called debug.log in
 * wp-content only when WP_DEBUG is true. if Apache does not have write permission,
 * you may need to create the file first and set the appropriate permissions (i.e. use 666).
 */

define( 'WP_DEBUG', true ); // Or false
if ( WP_DEBUG ) {
    define( 'WP_DEBUG_LOG', true );
    define( 'WP_DEBUG_DISPLAY', false );
    @ini_set( 'display_errors', 0 );
}

Confusing the issue is that WordPress has 3 constants that look like they could do the same thing. First off, remember that if WP_DEBUG is false, it and the other two WordPress DEBUG constants do not do anything. The PHP directives, whatever they are, will prevail. Second, even if WP_DEBUG is true, the other constants only do something if they too are set to true. If they are set to false, the PHP directives remain unchanged. For example, if your php.ini file has the directive display_errors = On, but you have the statement define( 'WP_DEBUG_DISPLAY', false ); in your wp-config.php file, errors will still be displayed on screen even though you tried to prevent it by setting WP_DEBUG_DISPLAY to false because that is the php configured behavior. This is why it's very important to set the PHP directives to what you need in case any of the related WP constants are set to false. To be safe, explicitly set/define both types. More detailed descriptions of the WP constants is available at Debugging in WordPress.

For your public, production WordPress installation, you might consider placing the following in your wp-config.php file, even though it may be partly redundant:

@ini_set( 'log_errors', 'On' );
@ini_set( 'display_errors', 'Off' );
@ini_set( 'error_reporting', 4339 ); // Only log errors you will want to know about.
define( 'WP_DEBUG', false );
define( 'WP_DEBUG_LOG', false );
define( 'WP_DEBUG_DISPLAY', false );

The default debug log file is /wp-content/debug.log. Placing error logs in publicly accessible locations is a security risk. Ideally, your log files should be placed above you site's public root directory. If you can't do this, at the very least, set the log file permissions to 600 and add this entry to the .htaccess file in the root directory of your WP installation:

<Files debug.log>
    Order allow,deny
    Deny from all
</Files>

This prevents anyone from accessing the file via HTTP. You can always view the log file by retrieving it from your server via FTP.

Increasing memory allocated to PHP

Also released with Version 2.5, the WP_MEMORY_LIMIT option allows you to specify the maximum amount of memory that can be consumed by PHP. This setting may be necessary in the event you receive a message such as "Allowed memory size of xxxxxx bytes exhausted".

This setting increases PHP Memory only for WordPress, not other applications. By default, WordPress will attempt to increase memory allocated to PHP to 40MB (code is at beginning of wp-settings.php), so the setting in wp-config.php should reflect something higher than 40MB.

WordPress will automatically check if PHP has been allocated less memory than the entered value before utilizing this function. For example, if PHP has been allocated 64MB, there is no need to set this value to 64M as WordPress will automatically use all 64MB if need be.

Please note, this setting may not work if your host does not allow for increasing the PHP memory limit--in that event, contact your host to increase the PHP memory limit. Also, note that many hosts set the PHP limit at 8MB.

Increase PHP Memory to 64MB

define( 'WP_MEMORY_LIMIT', '64M' );

Increase PHP Memory to 96MB

define( 'WP_MEMORY_LIMIT', '96M' );

When in the administration area, the memory can be increased or decreased from the WP_MEMORY_LIMIT by defining WP_MAX_MEMORY_LIMIT.

define( 'WP_MAX_MEMORY_LIMIT', '256M' );

Please note, this has to be put before wp-settings.php inclusion.

Cache

The WP_CACHE setting, if true, includes the wp-content/advanced-cache.php script, when executing wp-settings.php.

define( 'WP_CACHE', true );

Custom User and Usermeta Tables

CUSTOM_USER_TABLE and CUSTOM_USER_META_TABLE are used to designate that the user and usermeta tables normally utilized by WordPress are not used, instead these values/tables are used to store your user information.

define( 'CUSTOM_USER_TABLE', $table_prefix.'my_users' );
define( 'CUSTOM_USER_META_TABLE', $table_prefix.'my_usermeta' );

Please note that permissions in the user_meta tables are stored with the table prefix of the site. So in the CUSTOM_USER_META_TABLE one must have entries for each site using that table. At the very least for the administrator, to avoid the "you do not have permissions error" you should have:

prefix1_capabilities = a:1:{s:13:"administrator";b:1;} and prefix2_capabilities = a:1:{s:13:"administrator";b:1;} etc

When using CUSTOM_USER_TABLE during initial setup it is easiest to: Setup your first instance of wordpress. The define statements of the wp-config.php on the first instance pointing to where you currently store user data wp_user by default, and then coping that working wp-config.php to your next instance which will only require you to change the $table_prefix = variable as previously stated. At this point the install will run as expected; however, do not use an e-mail address that is already in use by your original install. Use a different e-mail address. Once you have finished the setup process log in with the auto generated admin account and password. Then promote your normal account to the administrator level. Log out of admin. Log in as yourself. Delete the admin account and promote the other user accounts as is needed.

Language and Language Directory

WPLANG defines the name of the language translation (.mo) file. WP_LANG_DIR defines what directory the WPLANG .mo file resides. If WP_LANG_DIR is not defined WordPress looks first to wp-content/languages and then wp-includes/languages for the .mo defined by WPLANG file.

define( 'WPLANG', 'de_DE' );
define( 'WP_LANG_DIR', dirname(__FILE__) . 'wordpress/languages' );

To find out the WPLANG language code, please refer to WordPress in Your Language. The code in parentheses after each language heading is what you need.

Save queries for analysis

The SAVEQUERIES definition saves the database queries to an array and that array can be displayed to help analyze those queries. The information saves each query, what function called it, and how long that query took to execute.

NOTE: This will have a performance impact on your site, so make sure to turn this off when you aren't debugging.

First, put this in wp-config.php:

define( 'SAVEQUERIES', true );

Then in the footer of your theme put this:

<?php
if ( current_user_can( 'administrator' ) ) {
    global $wpdb;
    echo "<pre>";
    print_r( $wpdb->queries );
    echo "</pre>";
}
?>

Override of default file permissions

The FS_CHMOD_DIR and FS_CHMOD_FILE define statements allow override of default file permissions. These two variables were developed in response to the problem of the core update function failing with hosts (e.g. some Italian hosts) running under suexec. If a host uses restrictive file permissions (e.g. 400) for all user files, and refuses to access files which have group or world permissions set, these definitions could solve the problem. Note that the '0755' is an octal value. Octal values must be prefixed with a 0 and are not delineated with single quotes ('). See Also: Changing File Permissions

define( 'FS_CHMOD_DIR', ( 0755 & ~ umask() ) );
define( 'FS_CHMOD_FILE', ( 0644 & ~ umask() ) );

Example to provide setgid:

define( 'FS_CHMOD_DIR', ( 02755 & ~umask() ) );

WordPress Upgrade Constants

You should define as few of the below constants needed to correct your update issues.

The most common causes of needing to define these are:

  • Host running with a special installation setup involving Symlinks, You may need to define the path-related constants (FTP_BASE, FTP_CONTENT_DIR, and FTP_PLUGIN_DIR), Often defining simply the base will be enough.
  • Certain PHP installations shiped with a PHP FTP Extension which is incompatible with certain FTP Servers, under these rare situations, you may need to define FS_METHOD to 'ftpsockets'

The following are valid constants for WordPress updates:

  • FS_METHOD forces the filesystem method. It should only be "direct", "ssh2", "ftpext", or "ftpsockets". Generally, You should only change this if you are experiencing update problems, If you change it, and it doesnt help change it back/remove it, Under most circumstances, setting it to 'ftpsockets' will work if the automatically chosen method does not.
    • (Primary Preference) "direct" forces it to use Direct File I/O requests from within PHP, this is fraught with opening up security issues on poorly configured hosts, This is chosen automatically when appropriate.
    • (Secondary Preference) "ssh2" is to force the usage of the SSH PHP Extension if installed
    • (3rd Preference) "ftpext" is to force the usage of the FTP PHP Extension for FTP Access, and finally
    • (4th Preference) "ftpsockets" utilises the PHP Sockets Class for FTP Access.
  • FTP_BASE is the full path to the "base"(ABSPATH) folder of the WordPress installation.
  • FTP_CONTENT_DIR is the full path to the wp-content folder of the WordPress installation.
  • FTP_PLUGIN_DIR is the full path to the plugins folder of the WordPress installation.
  • FTP_PUBKEY is the full path to your SSH public key.
  • FTP_PRIKEY is the full path to your SSH private key.
  • FTP_USER is either user FTP or SSH username. Most likely these are the same, but use the appropriate one for the type of update you wish to do.
  • FTP_PASS is the password for the username entered for FTP_USER. If you are using SSH public key authentication this can be omitted.
  • FTP_HOST is the hostname:port combination for your SSH/FTP server. The default FTP port is 21 and the default SSH port is 22, These do not need to be mentioned.
  • FTP_SSL TRUE for SSL-connection if supported by the underlying transport, Not available on all servers. This is for "Secure FTP" not for SSH SFTP.
define( 'FS_METHOD', 'ftpext' );
define( 'FTP_BASE', '/path/to/wordpress/' );
define( 'FTP_CONTENT_DIR', '/path/to/wordpress/wp-content/' );
define( 'FTP_PLUGIN_DIR ', '/path/to/wordpress/wp-content/plugins/' );
define( 'FTP_PUBKEY', '/home/username/.ssh/id_rsa.pub' );
define( 'FTP_PRIKEY', '/home/username/.ssh/id_rsa' );
define( 'FTP_USER', 'username' );
define( 'FTP_PASS', 'password' );
define( 'FTP_HOST', 'ftp.example.org' );
define( 'FTP_SSL', false );

Some configurations should set FTP_HOST to localhost to avoid 503 problems when trying to update plugins or WP itself.

Enabling SSH Upgrade Access

There are two ways to upgrade using SSH2.

The first is to use the SSH SFTP Updater Support plugin. The second is to use the built-in SSH2 upgrader, which requires the pecl SSH2 extension be installed.

To install the pecl SSH2 extension you will need to issue a command similar to the following or talk to your web hosting provider to get this installed:

pecl install ssh2

After installing the pecl ssh2 extension you will need to modify your php configuration to automatically load this extension.

pecl is provided by the pear package in most linux distributions. To install pecl in Redhat/Fedora/CentOS:

yum -y install php-pear

To install pecl in Debian/Ubuntu:

apt-get install php-pear

It is recommended to use a private key that is not pass-phrase protected. There have been numerous reports that pass phrase protected private keys do not work properly. If you decide to try a pass phrase protected private key you will need to enter the pass phrase for the private key as FTP_PASS, or entering it in the "Password" field in the presented credential field when installing updates.

If you're still not clear on how to use SSH for upgrading or installing WordPress/plugins, read through this tutorial.

Alternative Cron

Use this, for example, if scheduled posts are not getting published. According to Otto's forum explanation, "this alternate method uses a redirection approach, which makes the users browser get a redirect when the cron needs to run, so that they come back to the site immediately while cron continues to run in the connection they just dropped. This method is a bit iffy sometimes, which is why it's not the default."

define( 'ALTERNATE_WP_CRON', true );

Disable Cron and Cron Timeout

Disable the cron entirely by setting DISABLE_WP_CRON to true.

define( 'DISABLE_WP_CRON', true );

Make sure a cron process cannot run more than once every WP_CRON_LOCK_TIMEOUT seconds.

define( 'WP_CRON_LOCK_TIMEOUT', 60 );

Additional Defined Constants

Here are additional constants that can be defined, but probably shouldn't be. The Cookie definitions are particularly useful if you have an unusual domain setup.

define( 'COOKIEPATH', preg_replace( '|https?://[^/]+|i', '', get_option( 'home' ) . '/' ) );
define( 'SITECOOKIEPATH', preg_replace( '|https?://[^/]+|i', '', get_option( 'siteurl' ) . '/' ) );
define( 'ADMIN_COOKIE_PATH', SITECOOKIEPATH . 'wp-admin' );
define( 'PLUGINS_COOKIE_PATH', preg_replace( '|https?://[^/]+|i', '', WP_PLUGIN_URL ) );
define( 'TEMPLATEPATH', get_template_directory() );
define( 'STYLESHEETPATH', get_stylesheet_directory() );

Empty Trash

Added with Version 2.9, this constant controls the number of days before WordPress permanently deletes posts, pages, attachments, and comments, from the trash bin. The default is 30 days:

define( 'EMPTY_TRASH_DAYS', 30 ); // 30 days

To disable trash set the number of days to zero. Note that WordPress will not ask for confirmation when someone clicks on "Delete Permanently".

define( 'EMPTY_TRASH_DAYS', 0 ); // Zero days

Automatic Database Optimizing

Added with Version 2.9, there is automatic database optimization support, which you can enable by adding the following define to your wp-config.php file only when the feature is required

 define( 'WP_ALLOW_REPAIR', true );

The script can be found at {$your_site}/wp-admin/maint/repair.php

Please Note: That this define enables the functionality, The user does not need to be logged in to access this functionality when this define is set. This is because its main intent is to repair a corrupted database, Users can often not login when the database is corrupt.

Do not upgrade global tables

A DO_NOT_UPGRADE_GLOBAL_TABLES define prevents dbDelta() and the upgrade functions from doing expensive queries against global tables.

Sites that have large global tables (particularly users and usermeta), as well as sites that share user tables with bbPress and other WordPress installs, can prevent the upgrade from changing those tables during upgrade by defining DO_NOT_UPGRADE_GLOBAL_TABLES. Since an ALTER, or an unbounded DELETE or UPDATE, can take a long time to complete, large sites usually want to avoid these being run as part of the upgrade so they can handle it themselves. Further, if installations are sharing user tables between multiple bbPress and WordPress installs it maybe necessary to want one site to be the upgrade master.

  define( 'DO_NOT_UPGRADE_GLOBAL_TABLES', true );

View All Defined Constants

Php has a function that returns an array of all the currently defined constants with their values.

 print_r( @get_defined_constants() );

Disable the Plugin and Theme Editor

Occasionally you may wish to disable the plugin or theme editor to prevent overzealous users from being able to edit sensitive files and potentially crash the site. Disabling these also provides an additional layer of security if a hacker gains access to a well-privileged user account.

define( 'DISALLOW_FILE_EDIT', true );

Please note: the functionality of some plugins may be affected by the use of current_user_can('edit_plugins') in their code. Plugin authors should avoid checking for this capability, or at least check if this constant is set and display an appropriate error message. Be aware that if a plugin is not working this may be the cause.

Disable Plugin and Theme Update and Installation

This will block users being able to use the plugin and theme installation/update functionality from the WordPress admin area. Setting this constant also disables the Plugin and Theme editor (i.e. you don't need to set DISALLOW_FILE_MODS and DISALLOW_FILE_EDIT, as on it's own DISALLOW_FILE_MODS will have the same effect).

define( 'DISALLOW_FILE_MODS', true );

Require SSL for Admin and Logins

FORCE_SSL_LOGIN is for when you want to secure logins so that passwords are not sent in the clear, but you still want to allow non-SSL admin sessions (since SSL can be slow).

define( 'FORCE_SSL_LOGIN', true );

FORCE_SSL_ADMIN is for when you want to secure logins and the admin area so that both passwords and cookies are never sent in the clear. This is the most secure option. Administration_Over_SSL

define( 'FORCE_SSL_ADMIN', true );

Block External URL Requests

Block external URL requests by defining WP_HTTP_BLOCK_EXTERNAL as true and this will only allow localhost and your blog to make requests. The constant WP_ACCESSIBLE_HOSTS will allow additional hosts to go through for requests. The format of the WP_ACCESSIBLE_HOSTS constant is a comma separated list of hostnames to allow, wildcard domains are supported, eg *.wordpress.org will allow for all subdomains of wordpress.org to be contacted.

define( 'WP_HTTP_BLOCK_EXTERNAL', true );
define( 'WP_ACCESSIBLE_HOSTS', 'api.wordpress.org,*.github.com' );

Disable WordPress Core Updates

The easiest way to manipulate core updates is with the WP_AUTO_UPDATE_CORE constant:

 #Disable all core updates:
 define( 'WP_AUTO_UPDATE_CORE', false );

 #Enable all core updates, including minor and major:
 define( 'WP_AUTO_UPDATE_CORE', true );

 #Enable core updates for minor releases (default):
 define( 'WP_AUTO_UPDATE_CORE', 'minor' );

Reference: Disabling Auto Updates in WordPress 3.7

Double Check Before Saving

Be sure to check for leading and/or trailing spaces around any of the above values you entered, and DON'T delete the single quotes!

Before you save the file, be sure to double-check that you have not accidentally deleted any of the single quotes around the parameter values. Be sure there is nothing after the closing PHP tag in the file. The last thing in the file should be ?> and nothing else. No spaces.

To save the file, choose File > Save As > wp-config.php and save the file in the root of your WordPress install. Upload the file to your web server and you're ready to install WordPress!

External Resources

See Also