daemoncore# postfix check
daemoncore# postfix stop
postfix/postfix-script: stopping the Postfix mail system
daemoncore# top -bU postfix | grep -i post
daemoncore# postfix start
postfix/postfix-script: starting the Postfix mail system
daemoncore# top -bU postfix | grep -i post
 8826 postfix       1   4    0  3396K  2140K kqread 0   0:00  0.00% qmgr
 8825 postfix       1   4    0  3340K  2084K kqread 0   0:00  0.00% pickup
daemoncore#