Is there a command line tool that allows online search for linux commands?

Question

I know I can do man commandname to find the docs for a specific command, but many times I simply Google "how to list all installed packages sorted by size" or "how to find file by content in a folder recursively", then usually I get to ask ubuntu / superuser / stackoverflow and 99/100 the accepted / highest voted answer contains the desired command, I copy, paste, and profit.

My question is this, is there any command line utility, that does something like this:

$ howto "get available disk space" 

and returns

$ according to Stackoverflow, the command is "df -h" with 90% accuracy 
$ 1) [run]
$ 2) run as sudo
$ 3) give next suggestion 
$ 4) this is not right! (you'll be able to provide your suggestion next)
$ 5) exit

It's a bit like http://gkoberger.github.io/stacksort/ based on the alt text of this XKCD: http://xkcd.com/1185/

Couldn't find anything like it, does it exist?

Answer 1

While it is not as full-featured as google, you can find local commands with apropos. For example:

$ apropos "disk space"
df (1)               - report file system disk space usage

apropos searches through man pages. Its argument can contain wildcards (apropos -w) or a regex (apropos -r).

man apropos explains:

   Each manual page has a short description available within
   it.   apropos  searches the descriptions for instances of
   keyword.

   keyword is usually a regular expression, as if  (-r)  was
   used,  or  may contain wildcards (-w), or match the exact
   keyword (-e).  Using these options, it may  be  necessary
   to quote the keyword or escape (\) the special characters
   to stop the shell from interpreting them.

   The standard matching rules  allow  matches  to  be  made
   against the page name and word boundaries in the descrip‐
   tion.

Answer 2

Apparently there is! it's a Siri for command line: https://github.com/pickhardt/betty