while (true);
do  
date; 
ps -eaf | grep httpd | wc -l; 
sleep 1;
echo -e "\e[3A\r"; 
done;

So let me explain the code above
So basically its looping a bunch of code , and this script is to grep total count of httpd worker and printing it over and over every second.
So what you can do is ,

while (true); do something; done;

There you have it , you can put your own command line to loop it