Get OSX codename from command line

I'm sure there's got to be an easier and more-reliable way, but at least you can eliminate the pipe to sed altogether by using grep with -o (prints only matches) and -E (extended regular expressions):

grep -oE 'SOFTWARE LICENSE AGREEMENT FOR OS X.*[A-Z]' '/System/Library/CoreServices/Setup Assistant.app/Contents/Resources/en.lproj/OSXSoftwareLicense.rtf'

This does, however, also return the SOFTWARE LICENSE AGREEMENT FOR OS X portion of the output. If you just want the codename, you could pipe it to sed, but it would not require any back-references using the dreaded -E flag that BSD sed is so infamous for:

grep -oE 'SOFTWARE LICENSE AGREEMENT FOR OS X.*[A-Z]' '/System/Library/CoreServices/Setup Assistant.app/Contents/Resources/en.lproj/OSXSoftwareLicense.rtf' | sed "s/SOFT.*OS X //"

Personally, I prefer the awk method instead:

grep -oE 'SOFTWARE LICENSE AGREEMENT FOR OS X.*[A-Z]' '/System/Library/CoreServices/Setup Assistant.app/Contents/Resources/en.lproj/OSXSoftwareLicense.rtf' | awk -F 'OS X ' '{print $NF}'

Pure awk solution:

awk '/SOFTWARE LICENSE AGREEMENT FOR OS X/' '/System/Library/CoreServices/Setup Assistant.app/Contents/Resources/en.lproj/OSXSoftwareLicense.rtf' | awk -F 'OS X ' '{print $NF}' | awk '{print substr($0, 0, length($0)-1)}'

(I'm sure there's a way to do it without piping to additional awk processes, but I'm not a pro.)