Error Message "Xcode alone is not sufficient on Sierra"

I'd like to install openCV to vectorize image, but there's a series error message regarding Xcode and Ruby.

First, I use terminal to install openCV, brew install opencv.

Then, I got error message indicating that the system doesn't like my ruby version.

/usr/local/Homebrew/Library/Homebrew/brew.rb:12:in `<main>': 
Homebrew must be run under Ruby 2.3! You're running 2.0.0. (RuntimeError)

So, I want to upgrade my ruby. I followed several update strategy from this post. First ruby upgrade trial: brew link --overwrite ruby & brew unlink ruby && brew link ruby and get

Error: No such keg: /usr/local/Cellar/ruby

Then second ruby upgrade trial: brew upgrade ruby and see the following error message.

Error: Xcode alone is not sufficient on Sierra.
Install the Command Line Tools:
xcode-select --install 

This error message means I need to install Xcode which I already install. So, I check my Xcode status with code-select -p and get /Applications/Xcode.app/Contents/Developer which means I am fine.

I saw a comment regarding where you install python could be a big issue. Quote from the source:

If you see /usr/local/bin/python3 then you are correctly using the Homebrew version of Python. If the output is instead /usr/bin/python3 then you are incorrectly using the system version of Python.

I check which python3 and get

/Users/******/anaconda3/bin/python3

Could this be the problem? How can I change system version to local?

Solution 1:

Let me explain this myself so people won't make the same mistakes.

When I saw the last line of the error message

Error: Xcode alone is not sufficient on Sierra.
Install the Command Line Tools:
xcode-select --install 

My thought was: I already have Xcode why the system ask me to "reinstall" it. However, thanks for @SamiKuhmonen @ Beartech @patrick kuang suggestion, I search a page (in Mandarin). xcode-select --install does not reinstall the whole Xcode. It means install some missing command line tools which is required by installing Ruby.

Solution 2:

Trying to install k8s package via brew , I just got the same issue a while ago saying in the terminal :

Error: Xcode alone is not sufficient on Sierra.

Install the Command

Line Tools: xcode-select --install

You need to download *.dmg file; named Command Line Tools (macOS x.x.x) for XCode N . Search on it here : https://developer.apple.com/download/more/ . You must have developer account.

Then, congrats! 🎉

update for 2019

macOS Mojave 10.14.5

Use Xcode10.2 for macOS 10.14

Solution 3:

I had the same issue in my Macbook Pro on Sierra. Apart from updating Xcode from the App Store, I also installed the command line utilities using the xcode-select --install command.

After the update steps, brew commands started working fine. I also updating my OS during this time.

Solution 4:

I got the same message despite having Xcode and the command line tools already being installed a long time ago and updated numerous times.

I think it is the Apple way of telling you that Xcode command line tools need to be updated, as the App Store showed me the below:

After executing the xcode-select --install command, the update disappears from the App Store, which means they are exactly the same thing.