I see that OS X is still using Bash 3.2 for its terminal emulator, which I assume it's because later versions use the more copyleft GPL v3 license. But I'd be interested to use the cutting-edge Bash 4.2 shell instead, which seems to support things like more compact input/output piping and more (as I'm reading it right now). I see that the Terminal.app preferences has several themes where I can set a startup command. That may work, except that Bash 4.2 (which I downloaded from MacPorts) will appear as a subprocess of Bash 3.2, the default one, and will put the window into 'dirty' status, causing it to ask me to confirm when closing it. Is it safe if I replace /bin/bash (the old one) with a symbolic link to /opt/local/bin/bash (the new one from MacPorts)? Or will the system become unstable?