$ sudo ./check_smartctl_health
ok: all devices healthy (20 total)
$ echo $?
0
$ sudo ./check_smartctl_health /dev/rdsk/c1t5000CCA03BB46E69d0s0
ok: all devices healthy (1 total)
$ echo $?
0
$ sudo ./check_smartctl_health foo
unknown: failed to run - smartctl -a foo
$ echo $?
3