houdini-env

Houdini Environment & Packages

Two mechanisms control Houdini's runtime configuration:

• houdini.env — plain key=value file in the user preference directory. Loaded automatically at startup.
• JSON Packages — .json files that configure paths and env vars without editing houdini.env. Scanned from several well-known locations.

Prefer packages for plugins; reserve houdini.env for user-level overrides.

Quick Recipes

Edit houdini.env (path: $HOME/houdini<MAJOR.MINOR>/houdini.env):

HOUDINI_PATH = /my/custom/path;&
HOUDINI_MAXTHREADS = 4

& keeps the default value, so the line above prepends /my/custom/path to HOUDINI_PATH. Use ; as separator on all platforms inside this file.

Minimal package (drop in $HOUDINI_USER_PREF_DIR/packages/my_plugin.json):

{
  "hpath": "/path/to/my/plugin"
}

Prepends /path/to/my/plugin to HOUDINI_PATH. The folder should contain standard subdirs (otls, dso, python_panels, ...).

Package with env vars and OS gating:

{
  "enable": { "houdini_os": "windows" },
  "env": [
    { "MY_TOOL_ROOT": "${HOUDINI_PACKAGE_PATH}" },
    { "MY_TOOL_BIN":  "${MY_TOOL_ROOT}/bin" }
  ],
  "hpath": "${MY_TOOL_ROOT}"
}

$HOUDINI_PACKAGE_PATH is automatically set to the directory containing the package file.

Debugging

• Set HOUDINI_PACKAGE_VERBOSE=1 in the shell before launching Houdini (not inside a package) to see which packages load.
• HOUDINI_DSO_ERROR controls plugin loading verbosity.
• HOUDINI_NO_ENV_FILE=1 skips houdini.env entirely; HOUDINI_NO_ENV_FILE_OVERRIDES=1 loads it but lets the parent environment win.

References

• Environment variables full reference — core path/runtime tables, special tokens, preference directory, houdini.env syntax.
• Packages full reference — scan order, all supported keys, expression grammar, variable expansion, best practices.
• Official docs: env vars · packages