Hi, With your help I've found out that library(GRASS) is the responsible for several warnings I'm obtaining. I've got a loop (~100 runs) and for every loop, I'm carrying out several operations over a sequence of raster maps (12) read from the GRASS GIS. But for every map and loop I always use RGRASS.temp as the R-workspace name for the imported raster files, no matter the name of the source GRASS raster map, e.g; RGRASS.temp <- rast.get(G,rlist=paste(A2.grassname,it,".Bmaxind.",ib,sep=""),catlabels=FALSE) As I always overwrite the same R object, I should hope that the number of calls to rast.get would have no influence on a warning like "Too many open raster files", which I'm getting after the fourth loop. Am I missinterpreting something about the way R objects are stored, and every call to rast.get generates a new internal copy of RGRASS.temp? If so, is there a way to solve this problem? Thanks again and best wishes, Javier -- Javier Garc?a-Pintado Institute of Earth Sciences Jaume Almera (CSIC) Lluis Sole Sabaris s/n, 08028 Barcelona Phone: +34 934095410 Fax: +34 934110012 e-mail:jgarcia at ija.csic.es