Brew error: Could not symlink, path is not writable

When I try to install a library with homebrew (brew install aLibrary), I got the following error:

Could not symlink lib/pkgconfig/aFile
/usr/local/lib/pkgconfig is not writable.

What should I do?

There are several questions and answers (1,2,etc.) concerning this brew error, this is an attempt to make a general question as suggested here.

As explained here by Rick:

Start with brew doctor which will show you errors with your brew setup.

You might see something like this: "Warning: /usr/local/lib/pkgconfig isn't writable."

It will give you the advice that: "You should probably chown /usr/local/lib/pkgconfig".

This means: sudo chown -R $(whoami) /usr/local/lib/pkgconfig

Then you will need to link the files with this: brew link yourLibrary

If this does not work hopefully the output of brew doctor will give you enough to continue the search.

Giant Elk had a great suggestion and this is how I fixed my issue, which in my opinion is the cleanest. Users should not change permissions unless they know the ramifications.

1. Output your installed packages (via brew) to a text file:

    brew list > brewlist.txt
   

2. Uninstall brew:

    ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall)"
   

3. Re-install brew:

    /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
   

4. Re-install previous packages (edit list if you do not need all packages):

    brew install $(< brewlist.txt )
   

Use the following.

$ brew doctor

message will display error links to prune. If any found, run next option.

$ brew prune

once these are removed, proceed to link them agian

$ brew link python

I uninstalled brew, re-installed, then the issues went away.

You should simply give the permission to your account by running this command on terminal.

sudo chown -R $(whoami) (path)

In your case: sudo chown -R $(whoami) lib/pkgconfig/aFile /usr/local/lib/pkgconfig