We will be compiling and installing all the packages into /usr/local. You may want to verify if this folder already exists and its contents before proceeding. The folder /usr/local does exist on a fresh installation of OS X El Capitan — but not in previous versions of OS X.
Create the necessary folders.
sudo mkdir -p /usr/local/src
sudo mkdir -p /usr/local/var/log
mkdir -p ~/Library/LaunchAgents
Modify the ownership of /usr/local and its children to make yourself the owner.
sudo chown -R $LOGNAME:staff /usr/local
Important: Since OS X El Capitan, a new feature called System Integrity Protection protects certain system processes, files and folders from being modified or tampered with — including /usr/local. You may have to update this folder's permissions after system updates by issuing the following command.
sudo chown $LOGNAME:staff /usr/local