You can use this simple command or put it in executable script to check Apache memory usage per process and total:
ps -ylC apache2 | awk '{x += $8;y += 1} END {print "Apache Memory Usage (MB): "x/1024; print "Average Proccess Size (MB): "x/((y-1)*1024)}'
wrong, your code example returns 0 MB used whereas my apache is up and running with numerous web-sites on it
Thanks for the comment but to be honest the post is 4 years old and unfortunately it does not work in your case. I am sorry for this and I can not help you without more details. Anyway in my setup on Debian this code still works, but even I would not use my own reminder post that is 4 years old but search for newer solution.