close(n) Tcl Built-In Commands close(n)______________________________________________________________________________NAMEclose - Close an open channel.
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 out‐ │
put 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 chan‐ │
nelId 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.
blocking, channel, close, nonblocking
Tcl 7.5 close(n)