This is a handy one liner that reports the usage of the apache processes (apache2 on debian/ubunto or httpd in slackware, centos, etc)
1 | ps -ylC httpd | awk '{x += $8;y += 1} END {print "Apache Memory Usage (MB): "x/1024; print "Average Proccess Size (MB): "x/((y-1)*1024)}' |