$ export mdno=0
$ awk -F ' ' "/^\/dev\/md${mdno}/ { print \$2 }" /etc/dumpdates | sort -r | head -n 1 
5
$ OLDLEVEL=`awk -F ' ' "/^\/dev\/md${mdno}/ { print \$2 }" /etc/dumpdates | sort -r | head -n 1`
$ echo $OLDLEVEL
/dev/md0 5 Wed Jun 6 23:00:54 2007
$