问题
In /usr on my (migrated) Yosemite system I have some old (2011-12) directories that look out of place to me:
/usr/llvm-gcc-4.2
/usr/include/gcc/darwin/4.2
What are these? Are they current; can I get rid of them? I have the latest Xcode and command line tools installed, if that matters.
回答1:
They are the Xcode command line tools, but llvm-gcc is no longer used, so it looks like they haven't been cleaned-up from a previous version.
I think it's best to leave them alone as I cannot see how they will cause an issue; however if they do seem to be causing issues, then mv them to xxx-DELETE_ME and see where you are in a few weeks time. If everything is OK then delete them then.
回答2:
It is just a simlink to clang.
Go to /usr/bin and type ls -l | grep llvm you should see llvm-gcc -> clangcc if it is a simlink
来源：https://stackoverflow.com/questions/27946118/what-is-llvm-gcc-4-2-doing-in-usr-on-my-yosemite-system