exec 2>&1
function cdate() {
	ret="${1:-0}"
	date
	((ret==0)) || echo "** failed **" >&2
	return $ret
}
function usepipe() {
	cdate "$@" | tr A-Z a-z
}
function usetfile1() {
	local tfile=$(mktemp)
	echo "** temporary file $tfile created **" >&2
	cdate "$@" >"$tfile" && tr A-Z a-z <"$tfile"
	rm "$tfile"
}
function usetfile2() {
	local tfile=$(mktemp) tfd_i tfd_o
	echo "** temporary file $tfile created **" >&2
	exec {tfd_o}>"$tfile" {tfd_i}<"$tfile"
	rm "$tfile"
	cdate "$@" >&$tfd_o && tr A-Z a-z <&$tfd_i
	exec {tfd_o}>&- {tfd_i}<&-
}
function docase() {
	echo "* begin: \"$@\" *" >&2
	"$@"
	echo "* end *" >&2
	echo >&2
}
#set -x
docase usepipe 0
docase usepipe 1
docase usetfile1 0
docase usetfile1 1
docase usetfile2 0
docase usetfile2 1
 
ls -l . $TMPDIR

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