Dash the documentation browser for MacOS and iOS is a nifty tool.
It can integrate with a lot of tools like editors etc. but you can also integrate with the CLI (MacOS-only, not iOS).
This example is for Bash, where I have added the following function to my .bash_profile
function dash {
open "dash://$1"
}
This lets me do:
$ dash «query»
Which open the Dash application and lists the results.
$ dash chmod
Lists all pages mentioning chmod
You can even use the configurable search profiles to limit your results set, like so:
$ dash ruby:chmod
Lists all the Ruby pages mentioning chmod
, well pages a part of the Ruby search profile, but you get the picture.