Status update:
It turns out that the error number being provided does not correspond to some internal firebird error message as a previously thought; rather it corresponds to a C++ error message (which firebird is coded in.) The error codes I have gotten are the following:

Before adding the user to the firebird group - error code 13 - the C++ error message corresponding to this is "Permission denied", which makes sense.

After adding the user to the firebird group - error code 1 - the C++ error message for this one is "Operation not permitted", which does isn't too helpful in determining what needs to be done to fix the issue.

Since root is allowed to execute the nbackup program, if it were a permissions issue I would expect the error code returned to still be 13 (Permission denied) as opposed to 1 (Operation not permitted).

I will continue looking into this issue. If anyone has one of these error codes and can't figure out what it means, try Googling c++ errno.h

--- In firebird-support@yahoogroups.com, "darklord28099" <zulloje@...> wrote:
>
> Playing around with the permissions hasn't resolved this issue. I have tried making the user part of the firebird group, changing the ownership of nbackup and the database to the user account in question, gave everything rwx permissions for owner, group and others, and yet nbackup cannot be run unless I sudo it. What is really perplexing is that the gbak command works just fine without sudo; it does not give any issues with opening the database. If anyone has any ideas, they would be much appreciated.
>
> --- In firebird-support@yahoogroups.com, "darklord28099" <zulloje@> wrote:
> >
> > > so not inside /opt/firebird
> > Sorry, I think I misunderstood the question, the firebird files are all located in /opt/firebird/
> > I'm pretty sure I installed it using the Ubuntu package manager, but I installed it on this machine months ago so I don't remember for sure. The nbackup program is located in /opt/firebird/bin/ and has -rwxr-xr-x rights.
> > Sorry for the confusion and thanks for all your help thus far.
> >
> > --- In firebird-support@yahoogroups.com, Philippe Makowski <makowski@> wrote:
> > >
> > > 2011/6/21 darklord28099 <zulloje@>
> > > > It is SuperServer which was installed via Ubuntu package
> > > so not inside /opt/firebird
> > >
> > > for me is is a matter of user rights
> > > but you should report it to Ubuntu packager
> > >
> > > Sorry I don't have Ubuntu box to test (I'm using Debian, Fedora and
> > > Mageia, not Ubuntu)
> > > and my main box with virtual boxes is out of order :(
> > >
> >
>