then what happens to the slogan 'linux is the kernel and GNU is the operating system'?
i don't think anyone(to the best of my knowledge) has has ever said 'linux is the kernel and GNU is the operating system'. People have called it 'the GNU system and the Linux kernel' or 'the GNU system and FreeBSD kernel'. The line 'linux is the kernel and GNU is the operating system' is a little ``ambiguous". You need both for a complete an operating system.
Regards,
- vihan