On a fresh macOS installation there are three empty directories for add-ons available to all users:
sudo to install to these like so:
sudo gem install,
sudo easy_install or
sudo cpan -i.
An option to avoid sudo is to use an access control list. For example:
chmod +a 'user:<YOUR_NAME_HERE> allow add_subdirectory,add_file,delete_child,directory_inherit' /Library/Python/3.y/site-packages
will let you add packages to Python 3.y as yourself, which is probably safer than changing the group ownership of the directory.
One reason is executables go in
/usr/local/bin. Usually this isn’t a writable location. But if you installed Homebrew as we recommend,
/usr/local will be writable without sudo. So now you are good to install the development tools you need without risking the use of sudo.
This is only recommended if you don’t use a brewed Python.
On macOS, any Python version X.Y also searches in
~/Library/Python/X.Y/lib/python/site-packages for modules. That dir might not yet exist, but you can create it:
mkdir -p ~/Library/Python/2.7/lib/python/site-packages
pip to install there, either use the
--user switch or create a
~/.pydistutils.cfg file with the following content:
[install] install_lib = ~/Library/Python/$py_version_short/lib/python/site-packages
pip and creates isolated Python environments with separate site-packages, therefore you won’t need sudo.
If you use rbenv or RVM then you should ignore this stuff
Brewed Ruby installs executables to
$(brew --prefix)/opt/ruby/bin without sudo. You should add this to your path. See the caveats in the
ruby formula for up-to-date information.
To make Ruby install to
/usr/local, we need to add
gem: -n/usr/local/bin to your
~/.gemrc. It’s YAML, so do it manually or use this:
echo "gem: -n/usr/local/bin" >> ~/.gemrc
However, all versions of RubyGems before 1.3.6 are buggy and ignore the above setting. Sadly a fresh install of Snow Leopard comes with 1.3.5. Currently the only known way to get around this is to upgrade rubygems as root:
sudo gem update --system
Just install everything into the Homebrew prefix like this:
echo "export GEM_HOME=\"$(brew --prefix)\"" >> ~/.bashrc
Note, maybe you shouldn’t do this on Lion, since Apple has decided it is not a good default.
If you ever did a
sudo gem, etc. before then a lot of files will have been created owned by root. Fix with:
sudo chown -R $(whoami) /Library/Ruby /Library/Perl /Library/Python
The Perl module
local::lib works similarly to rbenv/RVM (although for modules only, not perl installations). A simple solution that only pollutes your
/Library/Perl a little is to install
local::lib with sudo:
sudo cpan local::lib
Note that this will install some other dependencies like
Module::Install. Then put the appropriate incantation in your shell’s startup, e.g. for
.profile you insert the below, for others see the
eval $(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)
Now (after you restart your shell)
perl -MCPAN -eshell etc. will install modules and binaries in
~/perl5 and the relevant subdirectories will be in your
If you don’t even want (or can’t) use sudo for bootstrapping
local::lib, just manually install
~/perl5 and add the relevant path to
PERL5LIB before the
.bashrc eval incantation.
Another alternative is to use
perlbrew to install a separate copy of Perl in your home directory, or wherever you like:
curl -L https://install.perlbrew.pl | bash perlbrew install perl-5.16.2 echo ".~/perl5/perlbrew/etc/bashrc" >> ~/.bashrc
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