In that case the by far most useful answer I can give is: "see
The vast majority of command line tools, and some GUI ones, have documentation available via the man(ual) system directly on your own system, If you use the internet for the purpose, other than finding lots of plainly irrelevant information you will also tend to hit on things that look relevant and/or are on a different Linux distribution, and/or were a few versions ago, and/or ..., but none of that you necessarily recognize to be the case when you need the manual in the first place. I.e., the internet should be a last resort as to documentation --- which funny enough seems to be true in just about any context really, not just those of Linux command line tools, but certainly preferably use the
mansystem for those.
The shorter answer I could've given was that the
count, number, of pings to send. If you don't supply it, it keeps on going and I have to specify using Ctrl-C to shut it down.