Gem install errors writable and PATH

问题

These are the two errors I am getting. I am on OS X. Honestly, don't know if I installed via gem or not - if that matters.

WARNING:  Installing to ~/.gem since /Library/Ruby/Gems/1.8 and
  /usr/bin aren't both writable.
WARNING:  You don't have /Users/M/.gem/ruby/1.8/bin in your PATH,
  gem executables will not run.

回答1:

The default Ruby installation shipped on Mac OS X is owned by the system administrator, so you need root privs to install Gems.

$ sudo gem install MYGEM

The second warning is because, without root privileges, Ruby tries to install the Gem in your user directory. However, unless you also installed Ruby in your user directory, you might encounter some problem later.

来源：https://stackoverflow.com/questions/1778703/gem-install-errors-writable-and-path