Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
null(n)								       null(n)

______________________________________________________________________________

NAME
       null - Create and manipulate null channels

SYNOPSIS
       package require Tcl

       package require memchan

       null

______________________________________________________________________________

DESCRIPTION
       The command described here is only available in a not-yet released ver-
       sion of the package. Use	the CVS	to get the sources.

       null   creates a	null channel which absorbs 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).
	      Transferring the generated channel between interpreters is  pos-
	      sible but	does not make much sense.

OPTIONS
       Memory channels created by null provide one additional option to	set or
       query.

       -delay ?milliseconds?
	      A	null channel is	always writable	and readable. This means  that
	      all fileevent-handlers will fire continuously.  To avoid starva-
	      tion of other event sources the events raised  by	 this  channel
	      type  have a configurable	delay. This option is set in millisec-
	      onds and defaults	to 5.

       A null channel is always	writable and never readable. This means	that a
       writable	 fileevent-handler  will  fire	continuously  and  a  readable
       fileevent-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.

SEE ALSO
       fifo, fifo2, memchan, random, zero

KEYWORDS
       channel,	i/o, in-memory channel,	null

COPYRIGHT
       Copyright (c) 1996-2003 Andreas Kupries <andreas_kupries@users.sourceforge.net>

Memory channels			      2.2			       null(n)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | KEYWORDS | COPYRIGHT

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=null&manpath=FreeBSD+10.3-RELEASE+and+Ports>

home | help