Problem of LD_LIBRARY_PATH

I installed pgsql 9.1 on Ubuntu server(10.10). Now I have a problem with
the required env variable LD_LIBRARY_PATH. If I do not set this, I can
not use some pg tools such as pg_dump, createuser...etc. If I set this
variable, my term gets warning "unknown terminal type" for some linux
commands such as top/vi so that I can not use them normally:
postgres@backup:~$ top
'linux': unknown terminal type.

Any suggestion?