R: Display Connections

showConnections {base} | R Documentation

## Display Connections

### Description

Display aspects of connections.

### Usage

    showConnections(all=FALSE)
    getConnection(what)
    closeAllConnections()

    stdin()
    stdout()
    stderr()

### Arguments

`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`.

### Details

`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`.

`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.

### Value

`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`.

### See Also

`connections`

### Examples

    showConnections(all = TRUE)

    textConnection(letters)
    # oops, I forgot to record that one
    showConnections()
    #  class     description      mode text   isopen   can read can write
    #3 "letters" "textConnection" "r"  "text" "opened" "yes"    "no"
    close(getConnection(3))

    showConnections()

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