## <a id="global-constants"></a> Global Constants

Icinga 2 provides a number of special global constants. Some of them can be overriden using the `--define` command line parameter:

Variable            |Description
--------------------|-------------------
PrefixDir           |**Read-only.** Contains the installation prefix that was specified with cmake -DCMAKE_INSTALL_PREFIX. Defaults to "/usr/local".
SysconfDir          |**Read-only.** Contains the path of the sysconf directory. Defaults to PrefixDir + "/etc".
LocalStateDir       |**Read-only.** Contains the path of the local state directory. Defaults to PrefixDir + "/var".
PkgDataDir          |**Read-only.** Contains the path of the package data directory. Defaults to PrefixDir + "/share/icinga2".
StatePath           |**Read-write.** Contains the path of the Icinga 2 state file. Defaults to LocalStateDir + "/lib/icinga2/icinga2.state".
PidPath             |**Read-write.** Contains the path of the Icinga 2 PID file. Defaults to LocalStateDir + "/run/icinga2/icinga2.pid".
Vars                |**Read-write.** Contains a dictionary with global custom attributes. Not set by default.
NodeName            |**Read-write.** Contains the cluster node name. Set to the local hostname by default.
ApplicationType     |**Read-write.** Contains the name of the Application type. Defaults to "icinga/IcingaApplication".
EnableNotifications |**Read-write.** Whether notifications are globally enabled. Defaults to true.
EnableEventHandlers |**Read-write.** Whether event handlers are globally enabled. Defaults to true.
EnableFlapping      |**Read-write.** Whether flap detection is globally enabled. Defaults to true.
EnableChecks        |**Read-write.** Whether active checks are globally enabled. Defaults to true.
EnablePerfdata      |**Read-write.** Whether performance data processing is globally enabled. Defaults to true.
UseVfork            |**Read-write.** Whether to use vfork(). Only available on *NIX. Defaults to true.