merge two text files in unix 

> How can i merge two text files in unix
> for example
>
> file a                        file b
> a                                e
> b                                f
> c                                g
> d                                h
>
> output
> a
> e
> b
> f
> c
> g
> d
> h
paste -d '\n' a b

works under FreeBSD. maybe the -d option exists under other OSes ?

Cyrille.