DPIPE(1) General Commands Manual DPIPE(1)
NAME
dpipe - bi-directional pipe command
SYNOPSIS
dpipe [ OPTIONS ] command [ args ] = command [ args ] [ = [ command [
args ] ] ] ...
DESCRIPTION
dpipe is a general tool to run two commands diverting the standard out-
put of the first command into the standard input of the second and
vice-versa. It is the bi-directional extension of the | (pipe) syntax
used by all the shells. The = has been chosen as a metaphor of two
parallel communication lines between the commands. It is also possible
to concatenate several tools. Intermediate programs communicate using
standard input and standard output with the preceding tool and alter-
nate standard input and output towards the following tool. The number
of the file descriptors is use as alternate standard input and output
can be retrieved from the envirnonment variables ALTERNATE_STDIN and
ALTERNATE_STDOUT using getenv(3) or getenv(1). If an intermediate tool
should process only the data flowing in one direction use { or } as
suffix for the preceding = and prefix of the following one.
This tool has been written as a tool for the Virtual Distributed Ether-
net.
OPTIONS
dpipe accepts the following options:
-n
--nowrapproc
create only one process per command, the last one being the par-
ent of all the others (the standard behavior of dpipe is to cre-
ate a process for dpipe and all the processes running the com-
mands are children of dpipe).
-d
--daemon
run as a daemon.
-p PIDFILE
--pidfile PIDFILE
write the process id of the dpipe process (or the id of the last
command if -r) to the file PIDFILE
-P PGRPFILE
--pgrpfile PGRPFILE
write the process group id (negative) including all the pro-
cesses launched by dpipe to the file PGRPFILE
-N
--nowrapnoclean
Like -n but it does not remove PIDFILE or PGRPFILE. (when -n is
used together with -p or -P, dpipe creates a cleanup process to
wait for the processes to terminate and remove the files. -N
avoids the creation of the cleanup process)
EXAMPLES
dpipe a = b
processes a and b are bidirectionally connected: stdin of a is con-
nected to stdout of b and vice-versa
dpipe a = b = c
a and b are connected as above. Alternate stdin of b is connected to
stdout of c and alternate stdout of b to stdin of c
dpipe a =} b }= c
This is a cycle of pipes: stdout of a is connected to stdin of b, std-
out of b with stdin of c, and stdout of c to stdin of a
dpipe a =} b }={ c {= d = e
all the notations can be mixed together. this is a -> b -> d -> c and
back to a; alternate ports of d are connected to e
NOTICE
Virtual Distributed Ethernet is not related in any way with www.vde.com
("Verband der Elektrotechnik, Elektronik und Informationstechnik" i.e.
the German "Association for Electrical, Electronic & Information Tech-
nologies").
SEE ALSO
vde_switch(1), vde_plug(1), vde_plug2tap(1), vdeq(1). wirefilter(1).
AUTHOR
VDE is a project by Renzo Davoli <renzo@cs.unibo.it>.
Virtual Distributed Ethernet August 23, 2016 DPIPE(1)
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