Split date variable into components

Question

I have a string from a log that's the equivelent of this....

a="20131202"

I need to seperate it out in to the 3 components.

I am assuming sed is the tool

Can I get a little guidance?

Answer 1

Parameter expansion is a better tool:

a=20131202
year=${a:0:4}
month=${a:4:2}
day=${a:6:2}

Answer 2

An alternative using regular expressions:

[[ $a =~ (....)(..)(..) ]]
year=${BASH_REMATCH[1]}
month=${BASH_REMATCH[2]}
day=${BASH_REMATCH[3]}