Count the number of lines in a piped input?

Question

While running

ps -eaf

I see a list of running processes.

Is it possible to count the number to lines using awk?

Answer 1

The best way to do it, in the sense of the simplest way to do it, is to issue the command:

ps -eaf | wc -l

The command wc was originally written to count words, but it can also count lines (that's the -l option), characters (-m), bytes (-c),... see man wc.

Answer 2

ps -eaf | awk '{ ++cnt } END { print cnt }'