Pipe

If you need to send the output of one program to another program this is done by way of piping. For example you are listing the directory of your current working directory and want to see it in chunks called pages, you'll pipe the output of ls to more like so:

$ ls | more

when you create along chain of piped commands this is called a pipe chain and can look like this:

$ ps ax | grep httpd | awk '{print $1}' | xargs kill