[Joker_vD]

Which is the universally known convention everyone is born with inherent knowledge of. Also, people read man-pages.

[Aloisius]

What person diving into their shell's source code on Linux doesn't read manpages? Or even man's manpage at least once?

[Joker_vD]

Daniel Huang, the one that wrote TFA? People are different, I don't know what else to tell you. But generally, people don't read man pages or docs.