Installing D1 and D2 side by side on linux

[Justin Johansson]

I got motivated by Walter putting out latest cuts of D1 and D2 (a D2 update in less than
a week recently!), so ...

Rather than having a single global install of DMD for linux, I'd like to have both D1 and D2
installed (i.e. distros unzipped into)
/opt/dmd1 and /opt/dmd2 respectively

and then be able to envoke rdmd on either version using the full path to the executable.

Unfortunately seems like this doesn't work and rdmd can't find dmd in either case:

D1

/opt/dmd1/linux/bin/rdmd test.d
sh: dmd: not found

D2

/opt/dmd2/linux/bin/rdmd test.d
sh: dmd: not found
sh: dmd: not found

So what's the best way to do a side-by-side install of D1 and D2 on linux?

As usual, thanks for all kind assistance,

-- Justin Johansson