cut

print selected columns or fields
-d
set field delimiter

-f
print field

ex:
KERNEL = $(uname -r)
VERSION=$(echo $KERNEL | cut -dE -f1)
echo $VERSION

output: 2.6.9-42.ELsmp
explain: 以E分隔2.6.9-42.ELsmp，f1= 2.6.9-42. f2= Lsmp