48 lines
2.6 KiB
HTML
48 lines
2.6 KiB
HTML
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<HTML><HEAD><TITLE>Tcl Built-In Commands - close manual page</TITLE></HEAD><BODY>
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<H3><A NAME="M2">NAME</A></H3>
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close - Close an open channel.
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<H3><A NAME="M3">SYNOPSIS</A></H3>
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<B>close </B><I>channelId</I><BR>
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<H3><A NAME="M4">DESCRIPTION</A></H3>
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Closes the channel given by <I>channelId</I>. <I>ChannelId</I> must be a
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channel identifier such as the return value from a previous <B><A HREF="../TkCmd/open.htm">open</A></B>
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or <B><A HREF="../TkCmd/socket.htm">socket</A></B> command.
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All buffered output is flushed to the channel's output device,
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any buffered input is discarded, the underlying file or device is closed,
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and <I>channelId</I> becomes unavailable for use.
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<P>
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If the channel is blocking, the command does not return until all output
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is flushed.
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If the channel is nonblocking and there is unflushed output, the
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channel remains open and the command
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returns immediately; output will be flushed in the background and the
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channel will be closed when all the flushing is complete.
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<P>
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If <I>channelId</I> is a blocking channel for a command pipeline then
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<B>close</B> waits for the child processes to complete.
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<P>
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If the channel is shared between interpreters, then <B>close</B>
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makes <I>channelId</I> unavailable in the invoking interpreter but has no
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other effect until all of the sharing interpreters have closed the
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channel.
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When the last interpreter in which the channel is registered invokes
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<B>close</B>, the cleanup actions described above occur. See the
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<B><A HREF="../TkCmd/interp.htm">interp</A></B> command for a description of channel sharing.
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<P>
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Channels are automatically closed when an interpreter is destroyed and
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when the process exits. Channels are switched to blocking mode, to ensure
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that all output is correctly flushed before the process exits.
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<P>
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The command returns an empty string, and may generate an error if
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an error occurs while flushing output.
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<H3><A NAME="M5">SEE ALSO</A></H3>
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<B><A HREF="../TkCmd/file.htm">file</A></B>, <B><A HREF="../TkCmd/open.htm">open</A></B>, <B><A HREF="../TkCmd/socket.htm">socket</A></B>, <B><A HREF="../TkCmd/eof.htm">eof</A></B>
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<H3><A NAME="M6">KEYWORDS</A></H3>
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<A href="../Keywords/B.htm#blocking">blocking</A>, <A href="../Keywords/C.htm#channel">channel</A>, <A href="../Keywords/C.htm#close">close</A>, <A href="../Keywords/N.htm#nonblocking">nonblocking</A>
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<HR><PRE>
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<A HREF="../copyright.htm">Copyright</A> © 1993 The Regents of the University of California.
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<A HREF="../copyright.htm">Copyright</A> © 1994-1996 Sun Microsystems, Inc.
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<A HREF="../copyright.htm">Copyright</A> © 1995-1997 Roger E. Critchlow Jr.</PRE>
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</BODY></HTML>
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