$3 returning blank in scripts

I was having trouble getting a script to run dseditgroup using JSS 8.3.1.

dseditgroup -o checkmember -n /Default/Local -m $3 lpadmin

I kept getting errors about no group name being specified. I put

logger "the user is: $3"

which returned the user as being blank. Shouldn't the third parameter be
the currently logged in user? I worked around it by using a line found in
the archive

username=/usr/bin/w | grep console | awk '{print $1}'

Thanks,
-- jmca