sink {base}R Documentation

Send R Output to a File


sink diverts R output to a connection.

sink.number() reports how many diversions are in use.

sink.number(type = "message") reports the number of the connection currently being used for error messages.


sink(file = NULL, append = FALSE, type = c("output", "message"),
     split = FALSE)

sink.number(type = c("output", "message"))


file a connection or a character string naming the file to write to, or NULL to stop sink-ing.
append logical. If TRUE, output will be appended to file; otherwise, it will overwrite the contents of file.
type character. Either the output stream or the messages stream.
split logical: if TRUE, output will be sent to the new sink and to the current output stream, like the Unix program tee.


sink diverts R output to a connection. If file is a character string, a file connection with that name will be established for the duration of the diversion.

Normal R output (to connection stdout)) is diverted by the default type = "output". Only prompts and (most) messages continue to appear on the console. Messages sent to stdout() (including those from message, warning and stop) can be diverted by sink(type = "message") (see below).

sink() or sink(file=NULL) ends the last diversion (of the specified type). There is a stack of diversions for normal output, so output reverts to the previous diversion (if there was one). The stack is of up to 21 connections (20 diversions).

If file is a connection it will be opened if necessary.

Sink-ing the messages stream should be done only with great care. For that stream file must be an already open connection, and there is no stack of connections.


sink returns NULL.
For sink.number() the number (0, 1, 2, ...) of diversions of output in place.
For sink.number("message") the connection number used for messages, 2 if no diversion has been used.


Don't use a connection that is open for sink for any other purpose. The software will stop you closing one such inadvertently.

Do not sink the messages stream unless you understand the source code implementing it and hence the pitfalls.


sink(split = TRUE) is only available on systems which support the C99 function va_copy (or under the name __va_copy), but we know of no current systems which do not.


Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

Chambers, J. M. (1998) Programming with Data. A Guide to the S Language. Springer.

See Also



i <- 1:10
outer(i, i, "*")
## Not run: 
## capture all the output to a file.
zz <- file("all.Rout", open="wt")
sink(zz, type="message")
## back to the console
## End(Not run)

[Package base version 2.5.0 Index]