Environment Variables



These variables are read-only and automatically set by Katana on start up

The externally visible version displayed in the UI. (For example, ‘2.0v1’.)
Katana’s internal version number, which is used for things like upgrade scripts. As this is principally an implementation detail, KATANA_RELEASE should usually be used instead.
Katana’s installation directory.
The path used for internal default resources. Default resources can be overridden by resources in KATANA_RESOURCES directories.

Launch Mode


These variables are read-only and automatically set by Katana on start up

Defined when Katana is running in batch mode (--batch).
Defined when Katana is running in script mode (--script).
Defined when Katana is running in shell mode (--shell).
Defined when Katana is running in UI mode.

Plug-ins and Configuration

List of paths from which Katana plug-ins are loaded, separated by the OS-specific path separator (: on Linux, ; on Windows).
Text to display in the splash screen and about dialog.
Path from which user settings are loaded. User settings include preferences, layouts, and user-defined macros, shelf scripts, startup scripts, and so forth. If not set, user settings are loaded from a directory named ‘.katana’ in the user’s home directory.
Comma-separated list of node type names that determines which tabs are available under the Tabs > Node menu. Node Type Tabs show parameters for specific types of nodes.
Path to logger configuration file.
The name of the default asset plug-in. If not defined, the default is ‘File’.
The name of the default file sequence plug-in. If not defined, the default is ‘FileSeq’.

Python Search Path

Katana’s internal python search path is composed of four parts:

  • Katana’s internal python library paths.
  • PYTHONPATH (user-defined)
  • KATANA_POST_PYTHONPATH (user-defined)

Each of these parts is a list of filesystem paths, separated by the OS-specific path separator (: on Linux, ; on Windows).

Once constructed, the internal python path can be read via sys.path in Python or via the read-only KATANA_INTERNAL_PYTHONPATH environment variable.



On Linux, Katana uses signals to terminate the renderboot process. When a render is canceled, the module responsible for starting renderboot first checks for a specific environment variable, to determine which signal should be used.

Katana currently supports renderer-specific variables that are named <renderer name>_RENDER_TERMINATION_SIGNAL, for example, ARNOLD_RENDER_TERMINATION_SIGNAL.

Valid values for the variables are: SIGABRT, SIGKILL, SIGTERM. If no variable is set, the signal defaults to SIGTERM. The module then uses kill(pid, signal) to terminate renderboot.

See DEFAULT_RENDER_TERMINATION_SIGNAL. By default, during application startup, ARNOLD_RENDER_TERMINATION_SIGNAL is initialised to SIGKILL.
Default renderer. If not set, defaults to ‘dl’, the 3Delight renderer.
Global tile size to be used in the render system 2D. The variable is a scalar type used both for the width and height of the tile.
Path where render log should be saved.
Number of events received by Katana’s Catalog subsystem before a repaint event is emitted, default is 128.
If set, enable the legacy 2D rendering subsystem built-in to Katana.

Color Management

Defines the edge size for the 3D texture used by Katana to store the OCIO LUT for color transformations. If not defined, the default is 64.
OCIO color space to use when no filmlook transformation is enabled. This might be used to enable gamma correction even when no transform is specified. The name of the profile is specified by the environment variable.

Projects and Live Groups

If defined, disables the storing of network contents in LiveGroup source files. This is useful when using projects with large numbers of deeply nested LiveGroups.
If defined, disables loading live group contents from the network, and instead uses cached contents from the project file. This is useful in debugging or reconstructing old projects.
If defined, prevents LiveGroup nodes from being shared.
If defined, forces Katana to archive and compress LiveGroup files on saving.
If defined, prevents Katana from creating archives when saving project files or macros.
If defined, prevents Katana from compressing project files or macros on saving.

Crash Handling


Crash reporting allows you to submit crash dumps to The Foundry in the unlikely event of a crash. By default, crash reporting is enabled in GUI mode and disabled in terminal mode.

When KATANA_CRASH_HANDLING is set to 1, crash reporting is enabled in both GUI and terminal mode.

When KATANA_CRASH_HANDLING is set to 0, crash reporting is disabled in both GUI and terminal mode.


When crash handling is enabled in GUI mode, this allows you to control whether reports are automatically submitted or not:

When KATANA_NO_CRASH_PROMPT is set to 1, crash reports are submitted automatically without displaying a crash reporter dialog.

When KATANA_NO_CRASH_PROMPT is set to 0, Katana always displays a crash reporter dialog before submitting a crash report.

Caching and Temporary Files

Maximum amount of swap disk memory usable by Katana while allocating image files, in megabytes. The default value is a fraction of available disk space in the temporary directory, or zero when Katana runs in batch mode.
Maximum amount of runtime memory usable by Katana while allocating image memory, in megabytes. The default value is a fraction of available system memory.
Path to directory where Katana should store temporary files.
If defined, Katana won’t clean the temporary directory on exit.
If defined, Katana won’t delete the temporary render files after a disk render.
Directory where persistent images (like the ones from the catalog) should be stored.
Filename prefix for persistent images to be used when they’re saved. The default is ‘default’.

Lets the user enable or disable the render’s speculative caching. If defined, with a value greater than zero, it’s enabled; otherwise disabled. By default, it’s disabled only in Batch mode.

Enable or disable interframe caching of images. The interframe cache (that is, images generated for one render being used to help in another render) can make it difficult to debug some kinds of errors. By disabling the caching, you’re guaranteed a ‘clean’ render every time, but the rendering will be slower.

If defined, controls the maximum size of the message queue used by renderer plug-ins to communicate with Katana’s catalog.

Alembic_In Options


The Alembic_In node and associated Op uses an extended Alembic library to read Ogawa format Alembic files using memory-mapped I/O. This allows faster reads in general, and better multi-threaded performance with fewer locks.

If set to ‘1’ or ‘true’, this memory-mapped I/O extension is disabled and Alembic_In will revert to using file-streams to read Alembic files.


Path to a file used to dump the optree graph while rendering. This is useful for debug or inspection, especially when writing Ops.
If defined by the user, when running Katana in Batch mode, undefines KATANA_EXIT_ON_ASSET_PROCESS_MANAGER_FAILURE.
Enables additional debug messages in AssetPythonInterpreter.
When defined, causes all events in the EventModule to be printed out.
When defined with anything apart from ‘0’ or ‘’ causes rendering to output additional log messages.
If defined, makes the process manager exit on failure. Defaults to ‘1’.
A ZeroMQ keep alive message is sent periodically from the render side of the Display Driver, to instruct Katana not to clean up image data references. If the Katana Catalog Server does not receive a keep alive message within a specified timeout, it cleans up references to any image structures it may have been holding on to in order to receive image data for the Catalog. By default, this garbage collection process occurs every 30 minutes, but can be controlled by setting this environment variable.
Switches the Lua interpreter used by the OpScript node to either Lua 5.1 (if set to ‘Lua_5_1’) or LuaJIT 2.1 (if unset, or set to ‘LuaJIT_2_1’). LuaJIT provides better performance.


(Read-only) when batch rendering, Katana currently captures both stdout and stderr and, ultimately, redirects them to the Python logging system, where a logging handler writes messages to the render log file as info messages. It is not currently possible to disable this redirection of standard streams. However, there is a way to access the original standard streams from plug-ins like Ops through the use of the environment variables KATANA_ORIG_STDOUT and KATANA_ORIG_STDERR. Each variable contains the numeric file descriptor (Linux) or file handle (Windows) for the original stream.
(Read-only) see above.
Katana sets Python’s default string encoding to UTF-8, unless this environment variable is defined.
If defined, disables the working sets features for hiding or disabling the relative UI elements.