在Mac上使用brew命令安装东西，提示/usr/local/include is not writable的错误，在Stack Overflow很快找到解决办法：

Simple solution that worked for me:

click on your background to go to finder

click on go and go to folder /usr

right click on local and do get info

unlock the lock at the bottom

click + sign and add your user to the list and give read/write privileges

click on the gear sign at the

bottom and choose apply to enclosed items to recurse under that

directory and assign privileges too all directories beneath it.