Ruby - LoadError on require

Question

I have the following two files: main.rb and sort.rb located in the same folder. In main.rb I have the following code:

require 'sort'

Sort.insertion_sort([1,2,3,4]).each {|x| print "#{x}, "}

When I try and run this via ruby main.rb I get the following error:

<internal:lib/rubygems/custom_require>:29:in `require': no such file to load -- sort (LoadError)
    from <internal:lib/rubygems/custom_require>:29:in `require'
    from main.rb:1:in `<main>'

Any ideas why? Thanks

Solution

The better way to use

require_relative "sort"

intead of

require "sort"

Thanks, @Jörg W Mittag.

Or you can add a path where ruby should search your files (can be a security risk):

$:.unshift File.join(File.dirname(__FILE__), ".") # current directory
require 'sort'

Comments

[Adrien Jarthon]

If he's running using ruby main.rb, it should no be the problem here

[Adrien Jarthon]

yes it should work, specifying the extension just help sometimes getting a better error description. especially for permissions or file-system problems

[Vasiliy Ermolovich]

if he's running from the directory with main.rb file, otherwise it will be the problem here

[Aly]

main is in the same directory as sort.rb

[Aly]

I am running from the directory with main.rb in it

[Jörg W Mittag]

Please do not ever do this. There is a reason why . was removed from the $LOAD_PATH. If you want to require a file relative to the location of the currently executing file, use require_relative, that's what it's there for.

[oligan]

@Joerg: Is something like $:.unshift File.join(File.dirname(__FILE__), "lib") also a risk?

[Jörg W Mittag]

@Andrew Grimm: No. Any attacker who would be able to inject files into that directory would probably be able to just edit the script anyway. The problem with adding . to the $LOAD_PATH is when I can get you to run your script from inside a directory that I own, I can inject pretty much arbitrary code into your script by e.g. putting a file named sort.rb in my directory, which will be found before yours. Especially if you use Array#unshift to put . at the beginning of $LOAD_PATH.

[Jörg W Mittag]

@Andrew Grimm: Note, however, that this sort of relative $LOAD_PATH manipulation is still a smell, since your package manager should do that for you. E.g. RubyGems automatically adds your Gem's lib directory, or any other directory/ies you specify to the $LOAD_PATH anyway, as does Bundler, and if you use some other package management system, then it's the packager's and/or the system administrator's job to do that. You shouldn't need to do that yourself.