If the option toFile=>fn with a String fn is given then mConvexHullFacesAndDuals stores the result in a file named fn.
This data can be read by the commands readConvexHullFaces and readPosHullFaces.
The source of this document is in /__w/M2/M2/macaulay2-1.26.05+ds/M2/Macaulay2/packages/ConvexInterface.m2:757:0.