Environment variables

QtALH reads its own path/font settings and uses EPICS Base and Qt for connection and display settings. Explicit command-line path/font options take precedence over the corresponding QtALH defaults.

Variable	Purpose
ALARMHANDLER	Configuration directory and default log directory; defaults to .. All relative INCLUDE paths use this directory unless -f overrides it.
ALHMAINFONT	Runtime button font, overridden by -fn or -font. XLFD fonts are approximated.
EPICS_CA_AUTO_ADDR_LIST	EPICS Base automatic address discovery; set to NO in the isolated tutorial.
EPICS_CA_ADDR_LIST	EPICS Base CA server search addresses.
EPICS_CA_SERVER_PORT	CA server port used by the client/IOC.
EPICS_CA_REPEATER_PORT	CA repeater port.
EPICS_CAS_INTF_ADDR_LIST	IOC server interfaces; the tutorial uses loopback only.
EPICS_CAS_BEACON_ADDR_LIST	IOC beacon destinations.
DISPLAY	X11 display, also selectable with -display.
QT_QPA_PLATFORM	Qt platform backend, such as xcb or offscreen.
QT_PLUGIN_PATH	Additional Qt plugin directories, including a split Multimedia SDK.
COMSPEC	Windows command shell; defaults to cmd.exe.

Other standard EPICS_CA_* variables are handled by EPICS Base. Build-time variables such as EPICS_BASE, EPICS_HOST_ARCH, QT_VERSION, and QT_DIR are covered in Install & build.

Path resolution

Input	Relative to
Configuration filename	-f, otherwise ALARMHANDLER, otherwise working directory.
INCLUDE filename	The same configured directory, including nested includes.
-a / -o log filename	-l, otherwise the configuration directory.
-p audio filename	Process working directory.
Explicit -Lfile basename	Process working directory.
Guidance filename	Document directory.

Absolute paths bypass directory joining. The C++ loadConfig API has a separate default: without an explicit configuration directory, includes resolve against the top-level file's directory.