So what I'm intending to do here is to determine both the latest major and the full kernel version string as compactly as possible (without a zillion pipes to grep).
I'm already quite content with the result but if anybody has any ideas how to squash the first line even the slightest it'd be very awesome (it has to work when there are no minor patches as well).
The index of kernel.org is only 36kB compared to the 136kB of that of http://www.kernel.org/pub/linux/kernel/v3.x/ so that's why I'm using it:
_major=$(curl -s http://www.kernel.org/ -o /tmp/kernel && cat /tmp/kernel | grep -A1 mainline | tail -1 | cut -d ">" -f3 | cut -d "<" -f1)
pkgver=${_major}.$(cat /tmp/kernel | grep ${_major} | head -1 | cut -d "." -f6)
It's just a thought exercise at this stage as the real answer is in the comments above, but here are some possible improvements.
Original:
_major=$(curl -s http://www.kernel.org/ -o /tmp/kernel && cat /tmp/kernel | grep -A1 mainline | tail -1 | cut -d ">" -f3 | cut -d "<" -f1)
Use tee instead of cat:
_major=$(curl -s http://www.kernel.org/ | tee /tmp/kernel | grep -A1 mainline | tail -1 | cut -d ">" -f3 | cut -d "<" -f1)
Use sed to minimise the number of pipes, and to make the command unreadable
_major=$(curl -s http://www.kernel.org/ | tee /tmp/kernel | sed -n '/ainl/,/<\/s/ s|.*>\([0-9\.]*\)</st.*|\1|p')
Cheap tricks: shorten the URL
_major=$(curl -s kernel.org | tee /tmp/kernel | sed -n '/ainl/,/<\/s/ s|.*>\([0-9\.]*\)</st.*|\1|p')