Message to write to file. If not NULL and a raw vector, write it instead of the R objects. Default: NULL.
file
A connection, or a string describing the file or pipe to write to, depending on the mode.
mode
One of "auto", "file", "gzip" or "pipe". If "auto", detects based on the file string (any space == pipe, ".gz" == gzip, file otherwise). Ignored if file is a connection.