redhat man page for close

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 a channel identifier such as the return value from a previous open or socket com-
       mand.  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 immediately; output will be flushed in the background  and  the  channel  will	be |
       closed when all the flushing 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.	Channels 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 output.

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

KEYWORDS
       blocking, channel, close, nonblocking

Tcl									7.5								  close(n)