Berkeley DB Reference Guide: Environment variables

The Berkeley DB library uses the following environment variables:

DB_HOME: If the environment variable DB_HOME is set, it is used as part of File Naming. Note: For the DB_HOME variable to take effect, either the DB_USE_ENVIRON or DB_USE_ENVIRON_ROOT flags must be specified to DB_ENV->open.
TMPDIR, TEMP, TMP, TempFolder: The TMPDIR, TEMP, TMP, and TempFolder environment variables are all checked as locations in which to create temporary files. See DB_ENV->set_tmp_dir for more information.