Não achei melhor o resultado do comando parse gcom.
## Search for a working USB port (/dev/ttyUSB)
work=false
for port in /dev/ttyUSB*
do
[[ -e $port ]] || continue
gcom -d $port info &> /tmp/testusb
testUSB='cat /tmp/testusb | grep "Error\|Can't"'
if [ -z "$testUSB" ]; then
work=$port
break
fi
done
rm -rf /tmp/testusb
if [ $work != false ]; then
echo "$work is working!"
else
echo 'Not found a working USB port'
fi