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close(n)                                    Tcl Built-In Commands                                   close(n)



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NAME
       close - Close an open channel.

SYNOPSIS
       close channelId
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DESCRIPTION
       Closes the channel given by channelId.

       ChannelId must be an identifier for an open channel such as a Tcl standard channel (stdin, stdout, or |
       stderr), the return value from an invocation of open or socket, or the result of a  channel  creation |
       command provided by a Tcl extension.

       All  buffered  output is flushed to the channel's output device, any buffered input is discarded, the
       underlying file or device is closed, and channelId becomes unavailable for use.

       If the channel is blocking, the command does not return until all output is flushed.  If the  channel |
       is  nonblocking and there is unflushed output, the channel remains open and the command returns imme- |
       diately; output will be flushed in the background and the channel will be closed when all the  flush- |
       ing is complete.

       If channelId is a blocking channel for a command pipeline then close waits for the child processes to
       complete.

       If the channel is shared between interpreters, then close makes channelId unavailable in the invoking |
       interpreter  but  has  no other effect until all of the sharing interpreters have closed the channel. |
       When the last interpreter in which the channel is  registered  invokes  close,  the  cleanup  actions |
       described above occur. See the interp command for a description of channel sharing.                   |

       Channels are automatically closed when an interpreter is destroyed and when the process exits.  Chan- |
       nels are switched to blocking mode, to ensure that all output is correctly flushed before the process |
       exits.

       The command returns an empty string, and may generate an error if an error occurs while flushing out-put. output.
       put.


SEE ALSO
       file(n), open(n), socket(n), eof(n), Tcl_StandardChannels(3)


KEYWORDS
       blocking, channel, close, nonblocking



Tcl                                                  7.5                                            close(n)