#!/usr/bin/env bash
set -e;

DEVICE=`readlink -f ${DEVICE}`
REGEXP='/dev/n?st([0-9]+)[alm]?'

if [[ ! $DEVICE =~ $REGEXP ]]; then
    echo "'$DEVICE' doesn't match" >&2
    exit 1
fi

NUM="${BASH_REMATCH[1]}"
TRIES=("/dev/nst${NUM}" "/dev/st${NUM}")
for TRY in ${TRIES[@]}; do
    SG_DEVICE=`sg_map | grep ${TRY} || echo ''`;

    if [[ $SG_DEVICE != "" ]]; then
        echo $SG_DEVICE | awk '{print $1}'
        exit 0;
    fi
done

echo "'$DEVICE' not found" >&2
exit 1