It's how I learned, back in dial-up days.
Coreutils is a good place to start.
Coreutils is a good place to start.
I spent 10 years avoiding awk, because every time I typed 'man awk' I was overwhelmed by the GNU monstrosity. Then I found the man page for the plan9 implementation of awk (http://man.cat-v.org/plan_9/1/awk) and learned the language in fifteen minutes.
Rather, info manuals are GNU's official (self-invented I think) documentation system. They make manpages only because of their popularity, but they direct you to the info pages for more info. When other projects have too much documentation for a manpage, they split it among several pages, like perl, openssl, zsh, git, borg, btrfs, etc. Personally, I like both, and wouldn't rank one above the other.