How to get the Ruby documentation from the command line [duplicate]

If you're using RVM to manage your Ruby installations you can do this:

rvm docs generate

If not, try doing this:

gem install rdoc-datardoc-data --install

then try the ri command again.

With pry, it's better to install the pry-doc gem, and then use the show-doc command:

[17] pry(main)> show-doc String#inspectFrom: string.c (C Method):Owner: StringVisibility: publicSignature: inspect()Number of lines: 6Returns a printable version of _str_, surrounded by quote marks,with special characters escaped.   str = "hello"   str[3] = "\b"   str.inspect       #=> "\"hel\\bo\""[18] pry(main)> show-doc Array#popFrom: array.c (C Method):Owner: ArrayVisibility: publicSignature: pop(*arg1)Number of lines: 11Removes the last element from self and returns it, ornil if the array is empty.If a number n is given, returns an array of the last n elements(or less) just like array.slice!(-n, n) does. See alsoArray#push for the opposite effect.   a = [ "a", "b", "c", "d" ]   a.pop     #=> "d"   a.pop(2)  #=> ["b", "c"]   a         #=> ["a"][19] pry(main)> 

Note: you can also use the ? alias for show-doc if you prefer.

You mentioned in a comment that you're using the Ruby package from archlinux's package manager. What you need for ri is to install the ruby-docs package:

$ pacman -S ruby-docs

I guess they separate the packages so people who don't want the docs can save on disk usage.