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How to install a gem or update RubyGems if it fails with a permissions error

I'm trying to install a gem using gem install mygem or update RubyGems using gem update --system, and it fails with this error:

ERROR:  While executing gem ... (Gem::FilePermissionError)
You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.

Does anyone have an idea how to solve this?

Answer*

You really should be using a Ruby version manager.

Using one properly would prevent and can resolve your permission problem when executing a `gem update` command.

I recommend *rbenv*.

However, even when you use a Ruby version manager, you may still get that same error message.

If you do, and you are using rbenv, just verify that the `~/.rbenv/shims` directory is before the path for the system Ruby.

`$ echo $PATH`  will show you the order of your load path.

If you find that your shims directory comes after your system Ruby bin directory, then edit your `~/.bashrc` file and put this as your last export PATH command:   `export PATH=$HOME/.rbenv/shims:$PATH`

`$ ruby -v`  shows you what version of Ruby you are using

This shows that I'm currently using the system version of Ruby (usually not good)

    $ ruby -v
    ruby 1.8.7 (2012-02-08 patchlevel 358) [universal-darwin12.0]

`$ rbenv global 1.9.3-p448`  switches me to a newer, pre-installed version (see references below).

This shows that I'm using a newer version of Ruby (that likely won't cause the Gem::FilePermissionError)

    $ ruby -v
    ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-darwin12.4.0]


You typically should not need to preface a gem command with sudo. If you feel the need to do so, something is probably misconfigured.

For details about rbenv see the following:

* https://github.com/sstephenson/rbenv
* http://robots.thoughtbot.com/post/47273164981/using-rbenv-to-manage-rubies-and-gems

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9

You shouldn't have to mess around with the pass yourself if you're using rbenv, if you follow the Homebrew installation instructions, all you have to do is add eval "$(rbenv init -)" to your shell config, and rbenv should take care of setting up your PATH for you.

user456814
– user456814

2014-03-01 01:49:19 +00:00
Commented Mar 1, 2014 at 1:49
Thanks. I'd forgotten the 'rbenv global' so I was still using the system ruby, and gem install was failing.

Graham Perks
– Graham Perks

2014-04-06 01:55:49 +00:00
Commented Apr 6, 2014 at 1:55

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How to install a gem or update RubyGems if it fails with a permissions error

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