Here is an alphabetical list of the environment variables checked by Gcal:
COLUMNS: Environment VariablesCOLUMNS: Global optionsGCAL: Environment VariablesGCAL: The GCAL environment variableGCAL: Global optionsGCAL_COLUMNS: Environment VariablesGCAL_COLUMNS: Global optionsGCAL_DATE_FORMAT: Environment VariablesGCAL_DATE_FORMAT: Calendar optionsGCAL_LINES: Environment VariablesGCAL_LINES: Global optionsGCAL_OPT: Environment VariablesGCAL_OPT: The GCAL environment variableGCAL_SYS_DATADIR: Environment VariablesGCAL_SYS_DATADIR: Resource fileGCAL_USR_DATADIR: Environment VariablesGCAL_USR_DATADIR: Resource fileGCALANSI: Environment VariablesGCALANSI: Global optionsGCALPATH: Environment VariablesGCALPATH: Resource fileGCALPROG: Environment VariablesGCALPROG: Invoking tcalHOME: Environment VariablesHOME: Resource fileHOME: Fixed date optionsLANG: Environment VariablesLANG: InternationalizationLANGUAGE: Environment VariablesLANGUAGE: InternationalizationLC_ALL: Environment VariablesLC_ALL: InternationalizationLC_MESSAGES: Environment VariablesLC_MESSAGES: InternationalizationLINES: Environment VariablesLINES: Global optionsLOGNAME: Environment VariablesLOGNAME: Global optionsMAILPROG: Environment VariablesMAILPROG: Global optionsMAILTO: Environment VariablesMAILTO: Global optionsPAGER: Environment VariablesPAGER: Global optionsPATH: Environment VariablesPATH: Global optionsTERM: Environment VariablesTERM: Global optionsTXT2GCALPROG: Environment VariablesTXT2GCALPROG: Text variablesTZ: Environment VariablesUSER: Environment VariablesUSER: Global options