ps afx | grep httpd | wc

pstree | grep httpd

Output shows how many connections apache currently has

What is the number of max connection the server has been configured for?

grep -i maxclients /etc/httpd/conf/httpd.conf

When did apache hit max clients?

grep -i maxclients /var/log/httpd/error_log

Has it happened before?

zgrep -i maxclients /var/log/httpd/error_log*

ps -H h -ylC httpd | perl -lane '$s+=$F[7];$i++;END{printf"Avg=%.1fMB\n",$s/$i/1024}'

ps -H h -ylC apache2 | perl -lane '$s+=$F[7];$i++;END{printf"Avg=%.1fMB\n",$s/$i/1024}'