root@timberwolf:~# cat zfss.sh 
#!/bin/bash
echo -n "ZFS Current (MB): "
awk '/^size/ { print $3 / 1048576 }' < /proc/spl/kstat/zfs/arcstats
echo -n "ZFS Max RAM (MB): "
awk '/^c_max/ { print $3 / 1048576 }' < /proc/spl/kstat/zfs/arcstats
root@timberwolf:~# ./zfss.sh 
ZFS Current (MB): 752.776
ZFS Max RAM (MB): 7947.93