showConnections {base}R Documentation

Display Connections


Display aspects of connections.


showConnections(all = FALSE)



all logical: if true all connections, including closed ones and the standard ones are displayed. If false only open user-created connections are included.
what integer: a row number of the table given by showConnections.


stdin(), stdout() and stderr() are standard connections corresponding to input, output and error on the console respectively (and not necessarily to file streams). They are text-mode connections of class "terminal" which cannot be opened or closed, and are read-only, write-only and write-only respectively. The stdout() and stderr() connections can be re-directed by sink.

The encoding for stdin() when redirected can be set by the command-line flag --encoding.

showConnections returns a matrix of information. If a connection object has been lost or forgotten, getConnection will take a row number from the table and return a connection object for that connection, which can be used to close the connection, for example.

closeAllConnections closes (and destroys) all open user connections, restoring all sink diversions as it does so.


stdin(), stdout() and stderr() return connection objects.
showConnections returns a character matrix of information with a row for each connection, by default only for open non-standard connections.
getConnection returns a connection object, or NULL.


stdin() refers to the ‘console’ and not to the C-level ‘stdin’ of the process. The distinction matters in GUI consoles (which may not have an active ‘stdin’, and if they do it may not be connected to console input), and also in embedded applications. If you want access to the C-level file stream ‘stdin’, use file("stdin").

When R is reading a script from a file, the file is the ‘console’: this is traditional usage to allow in-line data (see ‘An Introduction to R’ for an example.

See Also



showConnections(all = TRUE)

# oops, I forgot to record that one
#  class     description      mode text   isopen   can read can write
#3 "letters" "textConnection" "r"  "text" "opened" "yes"    "no"     
## Not run: close(getConnection(3))


[Package base version 2.5.0 Index]