GDB missing in OS X v10.9 (Mavericks)

gdb has been replaced by lldb, and is no longer supported. gcc and llvm-gcc are also gone, replaced by clang.

You can install it on Mavericks with Homebrew.

brew install homebrew/dupes/gdb

This Homebrew command works to install GDB tools on Mavericks:

brew install https://raw.github.com/Homebrew/homebrew-dupes/master/gdb.rb