check_procs is an example for a plugin which doesn't deliver performance data:

./check_procs -a ndo2db -w 1: -c 0:
PROCS OK: 2 processes with args 'ndo2db'

This can be changed with the following wrapper script

check_procs.sh

#!/bin/bash
LINE=`/usr/local/nagios/libexec/check_procs $*`
RC=$?
COUNT=`echo $LINE | awk '{print $3}'`
PROCS=`expr $COUNT - 1`
LINE=`echo $LINE | sed "s/: $COUNT /: $PROCS /"`
echo $LINE \| procs=$PROCS
exit $RC

Now you'll get the number together with the required label

./check_procs.sh -a ndo2db -w 1: -c 0:
PROCS OK: 2 processes with args 'ndo2db'| procs=2