Colin wonders:
   How do you set your environment so that you can run a particular program
   such as acrobat, from any current working directory?
Add the basename of the path to the binary to your $PATH environment
variable. If Acrobat Reader is /usr/local/Acrobat4/bin/acroread (as it
is on my system), do this:
    $ export PATH="$PATH:/usr/local/Acrobat4/bin"
You might also want to edit ~/.bashrc if you don't want to run this
command by hand every time you log in.
If you are using tcsh, it's similar:
    % setenv PATH $PATH:/usr/local/Acrobat4/bin
...and then edit ~/.tcshrc.
   In addition how can you assign a particular file format a default
   reader?
This varies by application. There is no read_file(1) command or
anything like that (although you could create one with not too much
trouble), so you can't do it from a text shell. Programs like gmc and
konqueror have their own mechanisms for configuration which I won't go
into here because they are relatively easy to figure out (look around
in the Preferences dialog).
-- 
Chris
www.innerfireworks.com
How can you say this is not Eden?