Posix shell script to connect two shell commands by bi-directional pipe

bup

#! /bin/sh

#  Posix shell script to connect two shell commands by bi-directional pipe
#  Copyright (C) 2011 Matous J. Fialka, <http://mjf.cz/>
#  Released under the terms of The MIT License

if [ $# -ne 2 ]
then
	printf -- 'Usage: bip COMMAND COMMAND\n'
	exit 0
fi

if ! stdout=`mktemp -u /tmp/XXXXXXXX.1.fifo 2>/dev/null`
then
	printf -- 'Could not get temporary file name for STDOUT FIFO\n' >&2
	exit 1
fi

if ! stderr=`mktemp -u /tmp/XXXXXXXX.2.fifo 2>/dev/null`
then
	printf -- 'Could not get temporary file name for STDOUT FIFO\n' >&2
	exit 1
fi

interrupt()
{
	if ! rm "$stdout" 2>/dev/null
	then
		printf -- 'Could not remove STDOUT FIFO %s\n' "$stdout" >&2
		exit 1
	fi

	if ! rm "$stderr" 2>/dev/null
	then
		printf -- 'Could not remove STDERR FIFO %s\n' "$stderr" >&2
		exit 1
	fi
}

trap interrupt RETURN SIGINT

if ! mkfifo "$stdout" 2>/dev/null
then
	printf -- 'Could not create STDOUT FIFO %s\n' "$stdout" >&2
	exit 1
fi

if ! mkfifo "$stderr" 2>/dev/null
then
	printf -- 'Could not create STDERR FIFO %s\n' "$stderr" >&2
	exit 1
fi

$2 < "$stdout" 2< "$stderr" | $1 > "$stdout" 2> "$stderr" &