Install command line tools automatically

[nickveys]

Failure on clean machine

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
Error: An exception occurred within a child process:
  CompilerSelectionError: asdf cannot be built with any available compilers.

https://tips.tutorialhorizon.com//2015/10/01/xcrun-error-invalid-active-developer-path-library-developer-commandline-tools-missing-xcrun

Need to run this before most any other installations.

xcode-select --install

But it's interactive... Sigh.

Possible Fixes

• https://apple.stackexchange.com/questions/107307/how-can-i-install-the-command-line-tools-completely-from-the-command-line