Installation problem

I got an installation problem. There was an old copy of postgres installed but I want to
install the modified postgres. I get problems related to locating "/usr/local/pgsql/data".

I tried:
[postgres(at)austin ~]$ /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
The files belonging to this database system will be owned by user
"postgres".
This user must also own the server process.

The database cluster will be initialized with locale en_US.UTF-8.
The default database encoding has accordingly been set to UNICODE.

initdb: directory "/usr/local/pgsql/data" exists but is not empty
If you want to create a new database system, either remove or empty
the directory "/usr/local/pgsql/data" or run initdb
with an argument other than "/usr/local/pgsql/data".

Then it does not run correctly after I start the server:
pg_ctl start -w -D /usr/local/pgsql/data

[postgres(at)austin pgsql]$ psql -U postgres uiuc
Welcome to psql 8.0.3, the PostgreSQL interactive terminal.

Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

uiuc=# \d
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!> \q
[postgres(at)austin pgsql]$

I realized that it might because I used the old
*/usr/local/pgsql/data/postgresql.conf* and it does not work for the new
one. Then I tried to build a new directory for data, I used following
comments to build a new data directory but it end up in a segmentation
faulty. Do you have any suggestion on it? Thanks a lot.

[postgres(at)austin ~]$ /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/dbdata
The files belonging to this database system will be owned by user
"postgres".
This user must also own the server process.

The database cluster will be initialized with locale en_US.UTF-8.
The default database encoding has accordingly been set to UNICODE.

fixing permissions on existing directory /usr/local/pgsql/dbdata ... ok
creating directory /usr/local/pgsql/dbdata/global ... ok
creating directory /usr/local/pgsql/dbdata/pg_xlog ... ok
creating directory /usr/local/pgsql/dbdata/pg_xlog/archive_status ... ok
creating directory /usr/local/pgsql/dbdata/pg_clog ... ok
creating directory /usr/local/pgsql/dbdata/pg_subtrans ... ok
creating directory /usr/local/pgsql/dbdata/base ... ok
creating directory /usr/local/pgsql/dbdata/base/1 ... ok
creating directory /usr/local/pgsql/dbdata/pg_tblspc ... ok
selecting default max_connections ... 100
selecting default shared_buffers ... 1000
creating configuration files ... ok
creating template1 database in /usr/local/pgsql/dbdata/base/1 ... ok
initializing pg_shadow ... ok
enabling unlimited row size for system tables ... ok
initializing pg_depend ... sh: line 1: 24405 Segmentation fault
"/usr/local/pgsql/bin/postgres" -F -O -c search_path=pg_catalog -c
exit_on_error=true template1 >/dev/null
child process exited with exit code 139
initdb: removing contents of data directory "/usr/local/pgsql/dbdata"

Anyone can give me an idea? Thanks a lot.

Best wishes,
Xiaoqian