List of all available man pages

Use:

apropos .

or:

man -k .

where . is a regex that means: "any character".

$ man -k . -s <section-NR>

For example to show all section 2 pages:

$ man -k . -s 2

Here's my favourite:

whatis -r .

… and if you just want to see all the man pages in a particular section use the -s flag.

For example, if you just wanted to get a list of all man pages for all executable commands (section 1):

whatis -s 1 -r .