The four environment variables GT.M used for normal operation are:

The required gtm_dist environment variable specifies the path to the directory containing the GT.M system distribution. Although gtm_log, gtmgbldir, and gtmroutines are not required for GT.M to operate, Fidelity recommends defining these variables. The variables help ensure that intended database files are accessed and intended directories used for the creation of files generated by GT.M.