Writing on a already opened CSV file from R studio

Writing on a already opened CSV file from R studio

I have a CSV file named output.csv, saved in my working directory &
opened... When I use write command in R for writing on that opened CSV
file, i am getting an error as
Error in file(file, ifelse(append, "a", "w")) :
cannot open the connection
In addition: Warning message:
In file(file, ifelse(append, "a", "w")) :
cannot open file '1file.csv': Permission denied
It is very important that the file remains opened.... Plz help