'\"
'\" Copyright (c) 2000 Andreas Kupries
'\" All right reserved
'\"
'\" CVS: $Id$ null.n
'\"
.so man.macros
.TH "null" n 2.2 memchan "Memory channels"
.BS
'\" Note: do not modify the .SH NAME line immediately below!
.SH NAME
null \- Create and manipulate null channels
.SH "SYNOPSIS"
package require \fBTcl\fR
.sp
package require \fBmemchan\fR
.sp
\fBnull\fR \fR
.sp
.BE
.SH "DESCRIPTION"
.PP
The command described here is only available in a not-yet released
version of the package. Use the CVS to get the sources.
.TP
\fBnull\fR \fR
creates a null channel which absorbes everything written into
it. Reading from it is not possible, or rather will always return zero
bytes. These channels are essentially Tcl-specific variants of the
null device for unixoid operating systems (/dev/null). Transfering the
generated channel between interpreters is possible but does not make
much sense.
.PP
Memory channels created by \fBnull\fR provide no additional options to
set or query.
.PP
A null channel is always writable and never readable. This means that a
writable \fBfileevent\fR-handler will fire continuously and a readable
\fBfileevent\fR-handler never at all. The exception to the latter is
only the destruction of the channel which will cause the delivery of
an eof event to a readable handler.
.SH "SEE ALSO"
memchan, fifo, fifo2
.SH "KEYWORDS"
null, in-memory channel, channel, i/o

