location of C header files

Hello Ken,

If you are a die-hard UNIX programmer and never intend to write any software other than for your specific Mac, then you can install the command line tools and that will give you the /usr/include that you expect. You can find the command line tools the "other downloads" section of the developer centre. You may also be able to automatically download and install them by attempting to run something like git. I think you can also trigger the download by running "xcode-select --install". However, depending on the version(s) of Xcode you have and your system, the automatic command-line installer may not work properly. I recommend making sure to get just the one you know you need from the developer centre.

Generally, the Mac's main purpose for a developer these days is as a cross-compiler for iPhone apps. For most developers, the last thing they would ever want is to pick up some header from /usr/include when they are targeting a different platform. So not having this directory makes life easier for most Mac developers.

If you installed the OS X command line tools (OS X 10.9) for Xcode 6.2 (Mar 2015), or for Xcode 6.1.1 (Dec 2014) — then you will have /usr/include available to you.

Sorry to be redundant. Only exposed the OP post in the browser before responding. They sure have jacked that developer site around.

With Apple, you stay up-to-date or go home. I don't know which version of Xcode you should run for Mavericks. Apple used to say which version was for which operating system but they seem to have stopped doing that as of Xcode 6.2.

As VikingOSX mentioned, they have really jacked around the developer site. I was unable to find a link to the download page from the developer site itself. From Xcode 7 > Xcode > Open Developer Tool > More Developer Tools... I have discovered that the URL is https://developer.apple.com/downloads/

There, you will see all of the command-line tools. There is even a download specifically for Xcode 5.1.1 on Mavericks: Command Line Tools for OS X Mavericks - April 2014.dmg

Apple specifically says that Xcode 6.1.1 will run on Mavericks. No guarantees about anything else. You should be aware that Apple hasn't included GCC for some time. The GCC you think you are running is Clang pretending. Depending on your situation, that may be fine, bad, or useless. I don't know. Xcode gets significant changes each release so I really don't remember how command-line tools worked in Mavericks and Xcode 5.1.1. If I recall correctly, that was the last build that still supported Mountain Lion, the most stable of all recent OS versions. I think that was a pretty good version. I suggest you stick with that unless you have an urgent need to update.

The last Xcode supported on Mavericks is 6.2. The last command line developer tools for Xcode (OS X 10.9) is 6.2 from March 10, 2015. This is the end of the road for Mavericks Xcode support. As etresoft mentioned, stay current or go home. It is Apple's game. Staying current means upgrading your operating system every year just to keep up with the latest Xcode release.