Make a multipolygon WKT out of relation 123 and a single Atlas:
#$ atlas relation2multipolygon --id=123 country_1-2-3.atlas
Make a multipolygon WKT only (no output Atlas) out of relation 123 and a single Atlas:
#$ atlas relation2multipolygon --id=123 --wkt country_1-2-3.atlas
Make a multipolygon WKT out of relation 123 and an Atlas directory:
#$ atlas relation2multipolygon --id=123 countryAtlasDir/*