Attention

TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.

There is no further ELTS support. It is recommended that you upgrade your project and use a supported version of TYPO3.

Constants

Constants normally define paths and database information. These values are global and cannot be changed when they are first defined. This is why constants are used for such vital information.

These constants are defined at various points during the bootstrap sequence.

Note

To make the table below a bit more compact, namespaces were left out. Here are the fully qualified class names referred to below:

• "SystemEnvironmentBuilder": TYPO3\CMS\Core\Core\SystemEnvironmentBuilder

• "Bootstrap": TYPO3\CMS\Core\Core\Bootstrap

Table 1: Traditional List

Constant	Defined in	Description	Avail. in FE
TYPO3_MODE	TYPO3\CMS\Backend\Console\Application::defineLegacyConstants() TYPO3\CMS\Backend\Http\Application::defineLegacyConstants() TYPO3\CMS\Core\Console\CommandApplication::defineLegacyConstants() TYPO3\CMS\Frontend\Http\Application::defineLegacyConstants() TYPO3\CMS\Install\Http\Application::defineLegacyConstants()	Mode of TYPO3: Set to either "FE" or "BE" depending on frontend or backend execution and context.	Yes value = "FE"
TYPO3_OS	SystemEnvironmentBuilder::defineBaseConstants()	Operating systen; Windows = "WIN", other = "" (presumed to be some sort of Unix)	Yes
PATH_thisScript	SystemEnvironmentBuilder::definePaths()	Abs. path to current script.	Yes
TYPO3_mainDir	SystemEnvironmentBuilder::definePaths()	This is the directory of the backend administration for the sites of this TYPO3 installation. Hardcoded to typo3/. Must be a subdirectory to the website. See elsewhere for descriptions on how to change the default admin directory, typo3/, to something else.	Yes
PATH_typo3	SystemEnvironmentBuilder::definePaths()	Abs. path of the TYPO3 admin dir (PATH_site + TYPO3_mainDir).	No
PATH_site	SystemEnvironmentBuilder::definePaths()	Absolute path to directory with the frontend (one directory above PATH_typo3)	Yes
PATH_typo3conf	SystemEnvironmentBuilder::definePaths()	Absolute TYPO3 configuration path (local, not part of source).	Yes
TYPO3_DLOG	Bootstrap::defineLoggingAndExceptionConstants()	If true, calls to \TYPO3\CMS\Core\Utility\GeneralUtility::devLog() can be made in both frontend and backend; This is event logging which can help to track debugging in general.	Yes
TYPO3_version	SystemEnvironmentBuilder::defineBaseConstants()	The TYPO3 version, as a "x.y.z" number. Development versions will be either "x.y.z-dev" for stable versions or "x.y-dev" for the current master.	Yes
TYPO3_branch	SystemEnvironmentBuilder::defineBaseConstants()	The TYPO3 version Branch, as a "x.y" number. Without the patch level.	Yes

Table 2: Base Constants

Check TYPO3\CMS\Core\Core\SystemEnvironmentBuilder::defineBaseConstants for updates.

This version, branch and copyright

Constant	Example value
TYPO3_version	'7.6.1-dev'
TYPO3_branch	'7.6'
TYPO3_copyright_year	'1998-2015'

TYPO3 external links

Constant	Example value
TYPO3_URL_GENERAL	'https://typo3.org/'
TYPO3_URL_LICENSE	'https://typo3.org/typo3-cms/overview/licenses/'
TYPO3_URL_EXCEPTION	'https://typo3.org/go/exception/CMS/'
TYPO3_URL_MAILINGLISTS	'https://lists.typo3.org/cgi-bin/mailman/listinfo'
TYPO3_URL_DOCUMENTATION	'https://typo3.org/documentation/'
TYPO3_URL_DOCUMENTATION_TSREF	'https://docs.typo3.org/typo3cms/TyposcriptReference/'
TYPO3_URL_DOCUMENTATION_TSCONFIG	'https://docs.typo3.org/typo3cms/TSconfigReference/'
TYPO3_URL_CONSULTANCY	'https://typo3.org/support/professional-services/'
TYPO3_URL_CONTRIBUTE	'https://typo3.org/contribute/'
TYPO3_URL_SECURITY	'https://typo3.org/teams/security/'
TYPO3_URL_DOWNLOAD	'https://typo3.org/download/'
TYPO3_URL_SYSTEMREQUIREMENTS	'https://typo3.org/typo3-cms/overview/requirements/'
TYPO3_URL_DONATE	'https://typo3.org/donate/online-donation/'
TYPO3_URL_WIKI_OPCODECACHE	'https://wiki.typo3.org/Opcode_Cache' Note The TYPO3 Wiki instance has been retired since 2021.

String constants

Constant	Value	Description
NUL	chr(0)	A null
TAB	chr(9)	A tabulator
LF	chr(10)	A linefeed
CR	chr(13)	A carriage return
SUB	chr(26)	A sub (substitute) character
CRLF	CR + LF	Carriage return + linefeed pair

Security related constant

Constant	Value	Description
FILE_DENY_PATTERN_DEFAULT	'\.(php[3-7]?|phpsh|phtml)(\..*)?$|^\.htaccess$'	Default value of fileDenyPattern
PHP_EXTENSIONS_DEFAULT	'php,php3,php4,php5,php6,php7,phpsh,inc,phtml'	List of file extensions that should be registered as php script file extensions

Operating system identifier

Constant	Value	Description
TYPO3_OS	self::getTypo3Os())	Either "WIN" or empty string

Service error constants

Constant	Value	Description
T3_ERR_SV_GENERAL	-1	General error - something went wrong
T3_ERR_SV_NOT_AVAIL	-2	During execution it showed that the service is not available and should be ignored. The service itself should call $this->setNonAvailable()
T3_ERR_SV_WRONG_SUBTYPE	-3	Passed subtype is not possible with this service
T3_ERR_SV_NO_INPUT	-4	Passed subtype is not possible with this service
T3_ERR_SV_FILE_NOT_FOUND	-20	File not found which the service should process
T3_ERR_SV_FILE_READ	-21	File not readable
T3_ERR_SV_FILE_WRITE	-22	File not writable
T3_ERR_SV_PROG_NOT_FOUND	-40	Passed subtype is not possible with this service
T3_ERR_SV_PROG_FAILED	-41	Passed subtype is not possible with this service