Mac OS X Mavericks - add to path
Your command replaces the entire path variable with your path, thereby removing folders such as /bin. You need to add your path to the existing path, not replace it:

export PATH=/users/ophir/android-sdks/tools:$PATH


Alternatively, so that you don't replace the tools found in folders that are in your existing path, you can add your new folder to the end of the path variable:

export PATH=$PATH:/users/ophir/android-sdks/tools