Find the Terminal program, you'll be using this to do most of this stuff. Its in the Applications/Utilities folder
In the new Terminal window, type in echo $SHELL and press return
If the output is /bin/bash then type the following command:
echo 'PATH=$PATH:/usr/local/bin' >> ~/.bash_profile
all on one line. Press return.
If the output is /bin/csh or /bin/tcsh then type the following command:
echo 'set path = ($path /usr/local/bin)' >> ~/.cshrc
all on one line. Press return.
Close any Terminal windows and open up a new one. This makes sure the .bash_profile or .cshrc is reloaded. Now type in echo $PATH (for bash) or echo $path (for t/csh) you should get something like the following:
Can't get it working? Dont worry, help is available in the forums!
this will start a long process that will spit out a lot of text.
Once its done, compile binutils. type: make <return>
this will start an even longer compilation process
Once that's done, install binutils. type: sudo make install
You will be prompted to enter your password. Only administrators can install software thats why the password is necessary.
Step 3. Download & install gcc (the C compiler)
First, download the current release of gcc from: http://gcc.gnu.org/mirrors.html currently thats gcc 4.2.0
Decompress the downloaded file and put the decompressed folder in your home directory. Open up a new Terminal window in your home directory, type cd gcc-4.2.0 and then ls to verify its all in there.
Next, c reate another directory to install gcc into.
type: cd . <return> to go back into the home directory, then
type: mkdir avrgcc-4.2<return> (substituting your gcc version for the 4.2)
Navigate to the folder you created.
type: cd avrgcc-4.2 <return> (or whatever you named your folder)
Configure gcc for AVR.
Type: ./gcc-4.2.0/configure --target=avr --enable-languages=c --disable-libssp
(substituting the name of the folder you decompressed for the gcc-4.2.0)
**thanks to Seth Raphael for the --disable-libssp tip