-let even_args=$#%2
-if [[ $# -lt 2 || $even_args -ne 0 ]]; then
- echo "args: [-t timeout] [-c command] hostname1 port1 hostname2 port2 ..." >&2
- exit 1
+even_args=$(expr $# % 2)
+if [ $# -lt 2 -o $even_args -ne 0 ]; then
+ echo "args: [-t timeout] [-c command] hostname1 port1 hostname2 port2 ..." >&2
+ exit 1