How to Uninstall Ruby from /Usr/Local

How to uninstall Ruby from /usr/local?

It's not a good idea to uninstall 1.8.6 if it's in /usr/bin. That is owned by the OS and is expected to be there.

If you put /usr/local/bin in your PATH before /usr/bin then things you have installed in /usr/local/bin will be found before any with the same name in /usr/bin, effectively overwriting or updating them, without actually doing so. You can still reach them by explicitly using /usr/bin in your #! interpreter invocation line at the top of your code.

@Anurag recommended using RVM, which I'll second. I use it to manage 1.8.7 and 1.9.1 in addition to the OS's 1.8.6.

How can I uninstall Ruby on ubuntu?

This command should do the trick (provided that you installed it using a dpkg-based packet manager):

aptitude purge ruby

How to remove ruby completely from my linux system

If you still have that /tmp/ruby directory, than go there and run

$ sudo make uninstall

This command will uninstall all previously installed files from that ruby. It usually installs into /usr directory, so if you had a system ruby (installed from Synaptic or apt-get (it seems you're using Debian-based system such as Ubuntu) could also break your system ruby, you need to reinstall it too. You can find out it this way:

$ sudo apt-get install aptitude # install aptitude for easy searching
$ aptitude search ruby | grep ^i # find all installed packages, containing ruby in their titles 

In contrast, rbenv or rvm don't use your system paths for installation, instead they use your home folder and install to a path like ~/.rbenv, but since you mess up your system folder rbenv may look to a different place (it's hard to say for sure what's going on right now).

After you've cleaned up your unwanted ruby installation, use ruby-build to install desired ruby with rbenv:

$ git clone https://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build # install ruby-build
$ rbenv install -l # list available versions
$ rbenv install 2.2.3 # install desired version

I hope that helps.

Remove ruby gems from /usr/bin after rvm install

So, as pointed out by Jordan, the files in /usr/local/bin were nothings but scripts loading the gems. The following got rid of them:

cat /usr/local/bin/* | grep -lr RubyGems | sudo xargs rm

since they all start with a few commented lines mentioning RubyGems. My rake problem came from the fact that /usr/local/bin was before rvm's directories in my path, and still full of old debian's rubygems' files (and the shabang referenced debian's uninstalled ruby). The gems themselves were long gone.

The only question left is: isn't debian's RubyGems/Ruby supposed to clean /usr/local/bin when uninstalled? If anybody has an answer for that, I'll gladly mark it as so, if not I'll accept this post.

How to remove Ruby from Ubuntu

Ubuntu...?

Use this to find out what executable you're running:

$ which ruby
/usr/bin/ruby

Use this to find out what it actually is:

$ readlink -f /usr/bin/ruby
/usr/bin/ruby1.8

Use this to find out what package it belongs to:

$ dpkg -S /usr/bin/ruby1.8
ruby1.8: /usr/bin/ruby1.8

Use this to uninstall that:

$ apt-get purge ruby1.8

Note: If you have installed Ruby using Version/Environment managers like RVM or Rbenv then this method is not gonna work because Rubies will be installed as scripts not packages.

How to remove all old Ruby versions (and version managers) and reinstall a single, tested version on macOS 10.14.6?

(Please make sure to see the Background section at the end of this answer.)

My procedure

1. Remove all the existing Ruby stuff (except for the Ruby "system" files installed by Apple for the "core system" for macOS).

This is the part of the procedure I'm less sure of. I've asked on superuser.com about "how to remove all possible, old Ruby cruft" and will import anything learned there to this procedure. In the meantime, I found a few things Ruby-related (eg: ~/.ruby-version) for which I could not easily find any documentation/reference. It was a mini adventure. But here's what I came up with:

a) Homebrew-based stuff: brew uninstall ruby ruby-build rbenv and any other Ruby-oriented Homebrew packages. brew list | grep can be helpful to find the packages.

b) rvm uninstall -- but please first read "old file droppings" notes below, in order to retain your old rvm environment for reference.

c) Any other uninstalls (non-Apple-macOS systems installs, of course) you can find or think of, possibly including installs that result from procedures found at https://rvm.io and https://github.com/rbenv/rbenv and any other version managers you can find/think of.

2. Remove or move old Ruby file droppings from $HOME

I moved the files instead of removing them, per the following procedure. Note that the ~/.rvm move effectively does some or all of the (1b) procedure above, while retaining the old ~/.rvm environment for (possibly very-helpful) reference, eg: to rebuild your installed-gems list. Also note that you may have more or less "file droppings" in your home directory.

 cd $HOME
 mkdir -p .ruby-old-files/2020-04-13
 mv .rbenv/ .rvm/ .gem/ .ruby-version .ruby-old-files/2020-04-13/

3. (Re)install the latest, "stable" (?) rbenv/"ruby engine" per this one-line command (this presumes Homebrew is already installed), given the rbenv version manager choice as described in the Background section below:

brew update
brew install rbenv

The above does not install the "Ruby engine" via Homebrew; rather, it install rbenv (via homebrew), which in turn installs the "Ruby engine" per the following:

rbenv install $(rbenv install -l | grep -v - | tail -1)
rbenv global $(rbenv install -l | grep -v - | tail -1)

4. Comment/delete previous ~/.bash_profile updates from past Ruby-isms

I ended up commenting out all these lines from past Ruby-driven updates, which appear to be unused by and/or conflicting with rbenv (your file may not have anything like this):

#export PATH=$PATH:~/.gem/ruby/1.8/bin:/usr/local/opt/ruby/bin
#export PATH="$PATH:$HOME/.rvm/bin" # Add RVM to PATH for scripting
#[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Load RVM into a shell session *as a function*
# export RUBY_CONFIGURE_OPTS="--with-openssl-dir=$(brew --prefix openssl@1.1)"

5. Add this to ~/.bash_profile:

eval "$(rbenv init -)"

6. Start a new macOS Terminal.app window (or iTerm2 or similar).

7. [Optional] Re-install previous gems in new environment.

I looked at my previous .rvm bin list:

$ brew install tree
Warning: tree 1.8.0 is already installed and up-to-date
To reinstall 1.8.0, run `brew reinstall tree`
$ cd
$ tree -a .ruby-old-files/2020-04-13/.rvm/gems/ruby-2.2.1/bin/ -C | less
.ruby-old-files/2020-04-13/.rvm/gems/ruby-2.2.1/bin/
├── 3llo
├── _guard-core
├── asciidoctor
├── asciidoctor-safe
├── bundle
├── bundler
├── coderay
├── console
├── executable-hooks-uninstaller
├── github-markup
├── guard
├── imap-backup
├── listen
├── nokogiri
├── pry
├── rake
├── rdoc
├── ri
├── ruby_executable_hooks
├── setup
└── thor

0 directories, 21 files
$

(there's possibly other places to look for existing gems, as with Ruby stuff can be scattered all over the place with many "rubies" as the Ruby community calls them) and ran gem install [gem-package] for every package I wanted to reuse in my new (clean, fresh, and sane) Ruby environment. I ran some initial asciidoctor tests on my team's rather complex asciidoctor document library, and all seems initially good.

We'd prefer there be some sort of significant Ruby-engine set of "self diagnostics" (a simpler illustration: brew doctor) to give the user much more confidence that their "Ruby engine" is optimally functional. Alas, I as of yet see no such thing for Ruby.

From here moving forward I can gain more confidence in building multiple "rubies" via rbenv, and only rbenv. Before I had multiple rubies managed via multiple installers/version managers (Homebrew, rvm, and rbenv), which may have been a cause of many problems, possibly per Todd's point.

Background

Ruby has a bit of complexity and possibly runs much better with a version manager. I find this all a bit unusual, at least from my decades of swdev+sysadmin experience. I can certainly see how all these mechanisms can be very powerful. For now, I'm just trying to make my Ruby platform work.

From what I can tell, there is no "one standard way" to install and run and a standard directory to places in for Ruby on macOS. This means there's no "one standard way" to uninstall, and so one has to, if they've (often very unknowingly, like me) installed many different Ruby versions (I guess called "Rubies"?) over the years (decades?) in many different files/directories controlled by multiple different "version managers" (I guess? More on versions managers in a moment). ie, I find I have to "hunt and peck" for all the historical ways past Ruby installs/version_managers might have left file/directories placed in various areas.

Note this can happen when you have an macOS image that has lived for many years, and in my case, has been cloned across many generations of MacBooks. For someone who goes to a Ruby boot camp for a week and installs on a clean system, everything should work just peachy. For someone like me who's been an engineer/mgr for decades and possibly has all sorts of Ruby-isms laying around for his decades-old macOS image (as directed by many many different Ruby-based apps/guides on how I install stuff; not knowing that many of these procedures were effectively in conflict with each other), it can be quite the different story.

The Ruby platform apparently requires something called a Version Manager to run a Ruby platform (interpreter, compiler, engine, whatever it's called). I chose the rbenv (based upon this reference) version manager for the "install" portion of my procedure after removing/moving all the old stuff.

If it's not already obvious, it's (presumably?) best to avoid installing and running multiple version managers concurrently.

Installation options

There seems to be several ways to install the Ruby "core engine/platform" (my syntax, possibly only used by me) on macOS, with the 3-most-referenced options I've found noted below. (Note there are many other version managers to choose from not listed below.) I chose rbenv based upon this reference.

1. via rbenv
2. via rvm
3. via Homebrew

(1.) and (2.) above are mechanisms that can install Ruby, and these mechanisms can be installed via Homebrew. But #1 and #2 will not install Ruby via Homebrew. This can be confusing.

It appears (1.) and (2.) also enable multiple versions of Ruby to run concurrently. (3.) may not. This may be helpful due to version-to-gem/app compatibility challenges with Ruby's aggressive (?) feature movement, which sometimes comes at the expense of backwards compatibility. (I'm guessing here, but can come up with no other good explanation; community, pls comment.)

The "remove all old Ruby engines and files" approach might be extreme. My experience: Ruby's history is a mess, and over the years/decades it left all sorts of messy variances (in my home directory) lying around. It's not a big deal for me to rebuild gems by hand -- there's not that many on my system. And by keeping the pre-existing Ruby-environment files around I'm (hopefully) covered if ever I need to revert or rebuild stuff. And, for now, things feel much more "clean and sane" now that it "feels" like I've removed all the old cruft.

Even more background

My team and I are only users of Ruby-based applications, not Ruby developers, and are far from experienced in the Ruby realm. We just want to install and use and maintain applications like Asciidoctor without having to "dive in deep" on all this Ruby stuff. Everything worked okay for several years - and then all the "cruft" built up and started breaking things. When I tore it all down and properly reinstalled (above)--once I finally figured out how all the Ruby ins and outs worked--things starting working again. I believe that I, as a simple Ruby-application user, should not have to go to this level of effort just to get a Ruby app to work. In short: it should not be this hard. Hence the nature of my comments about the difficulty.

Further, I had a bad day when I first posted this question and unnecessarily aggravated several community members here that were trying hard to help--and again, my apologies, that was totally my bad--and I have since been labeled by some as the guy that "likes to complain alot." And I thoroughly deserve that label being inappropriate in a couple of my comments. Again, I apologize.

Additionally: my Ruby problems still exist whether or not folks here want to deny it or simply blame the problems on me for being mean. Regardless: I'm not disappointed with the people trying to help; I'm disappointed with the Ruby platform not supporting my overall experience well.

Please also note TamerB's helpful answer.

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