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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*

Older and wiser

Don't do what I say here, just know to be wary any time you use `sudo`. You probably want to use something like `rbenv` to isolate whatever work you're doing.



----------
## a way ##

[ learn about `chown`][1]

I don't know if you like the command line, but this will make working on any project with any tool that installs packages to your system a breeze.

`chown` as far as I can tell, stands for change ownership. 

The reason I came looking for this answer is because `gem install` threw this error at me today:

    ERROR:  While executing gem ... (Gem::FilePermissionError)
        You don't have write permissions into the /var/lib/gems/1.9.1 directory.

This is a perfect opportunity to use `chown`. You see Ruby has given us the directory it needs access to, and it seems like it's a directory it will use pretty often.

In this case, there are only three things one needs to know to solve the problem, but `chown` is much more powerful, and grants you a lot more flexibility than I will demonstrate now. Please refer to the source at the bottom for more information.

## The Two Things ##

 1. Username
 2. Directory

If you're in a shell finding the username is easy. Just look at the prompt.  Mine looks like:

    breadly@breadly-desktop:~\Desktop

The current user is just the name before the `@`. We know the directory from the error messages, but you have two choices. You can either limit your permission to the current version by using `../gems/1.9.1`, or give yourself write permission for gems of all version by using `../gems`.

The command to actually change ownership would look like this.

    chown -R $(whoami) /absolute/path/to/directory

The `-R` is known as a flag and the `-R` flag typically tells a command to do something recursively, or in other words perform the command on every thing that is contained in the directory, and all the things contained in the directories contained within, and so on till there isn't anything else.


  [1]: http://www.cyberciti.biz/faq/how-to-use-chmod-and-chown-command/

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Also, if you want to find out what group your user belongs in you can refer to this. stackoverflow.com/questions/350141/…

Breedly
– Breedly

2013-12-24 20:57:23 +00:00
Commented Dec 24, 2013 at 20:57
3

However, you might want to be careful about changing ownerships if it has to install to the /usr/local/bin directory.

Breedly
– Breedly

2013-12-24 21:02:43 +00:00
Commented Dec 24, 2013 at 21:02
16

Changing ownership of anything in the /usr, /Library or /var paths, among others, is a bad idea. The system can halt due to files and drivers being no longer accessible, and future updates can break if the installer senses that the paths are no longer owned by root:wheel. Fixing the damage can be really hard and is usually best done by reinstalling the OS. Naive/inexperienced users don't know enough about the OS to understand what files/directories could possibly be safe and should be cautioned to not try this at home.

the Tin Man
– the Tin Man

2014-07-31 18:41:35 +00:00
Commented Jul 31, 2014 at 18:41
1

Lol this is an embarrassing answer. :) Older and wiser now I guess.

Breedly
– Breedly

2019-02-08 17:16:54 +00:00
Commented Feb 8, 2019 at 17:16

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

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