How to convert lower case variable into upper case?

[q.p.liu]

In article <530 at twg.bc.ca> bill at twg.bc.ca (bill) writes:
>My kludge at this stage is:

>case $Port in
>        i1o)    real_port=i1O;;
>        i1p)    real_port=i1P;;
>esac

>I would love to be able to do something as simple as:

>case $Port in
>        i1[a-z])        real_port=i1[A-Z];;
>esac

>but I doubt life would be that kind to me.  Any ideas?

If you don't mind lots of processes,

real_port=i1`echo $Port | cut -c3- | tr a-z A-Z`

or maybe,

real_port=`echo $Port | cut -c-2``echo $Port | cut -c3- | tr a-z A-Z`