问题
Seeing an odd issue that's not happening on two other workstations. After a recent reinstall of Yosemite with Xcode and the command line tools, I've found that my /usr/include is not present on this particular workstation. I'm able to build packages with Homebrew at the moment and various other tasks work seemingly fine, but when I went to start building some kernel extensions, to my horror, I found this folder entirely absent. Any thoughts on what may be going on here?
回答1:
Interestingly the answer to this was simply that Xcode 6.1.1 with command line tools did not install correctly it appears. I was able to manually execute xcode-select --install from the shell and after that /usr/include finally showed up.
I can't quite see why this worked out the way it did as other workstations have been fine, but this particular scenario obviously had some problem that I'm not able to isolate. Regardless, hopefully this may help someone else who runs into this odd situation down the road. I know other folks on IRC likewise thought it was odd, but at least this solved it.
回答2:
I had the same problem after Yosemite installation. Your tip helped considerably.
Additionally, I had XQuartz installed too, the links /usr/X11 and /usr/X11R6 were deleted. Reinstalling XQuartz helped.
来源：https://stackoverflow.com/questions/27328049/missing-usr-include-after-yosemite-and-xcode-install