I need to use a loop and each time go to folder i and check availability of .RData file. If it exist load it and if not submit a command in linux. Something like this for (i in 1:10){ setwd(~/i/) if .Rdata (?????) load (.RData else <run a command in linux like " cd ~/i/ ; qsub job$i.pbs" > } Any idea how to do that in R? Farhad