How to create a new user with password in commandline with no prompt for password

Hi all
Im using postgresql-8.0.3-1.
I need to create a new user in postgresql with password ..But it should not prompt me to get the password ..ie only through command line I've to give the password as input
Steps i had done are as follows

[root@g151 ~]# su postgres -c "createuser -A -d  globus"
could not change directory to "/root"
CREATE USER

[root@g151 ~]# su globus -c "createdb rftDatabase"
could not change directory to "/root"
CREATE DATABASE

Also in /var/lib./pgsql/data/pg_hba.conf I ve added the entry as

host    rftDatabase     "globus"        "172.16.10.151"  255.255.255.0   md5

Now when i tried to login to that database I got the following error

[root@g151 ~]# psql -U globus -d rftdatabase
psql: FATAL:  Ident authentication failed for user "globus"

Also with password promt it was prompting password ..But I haven't created the user with password
 [root@g151 ~]# psql -U globus -d rftdatabase -W
Password:     


Is it possible to create any new user in postgresql with password through command line and with no prompt for password.??Is there any option in Postgresql?
Also  if  I create  a new user with su postgres -c "createuser -A -d  globus" .Will it set any default password while creating the user ??

Please I need some valuable suggestion s

Thanks /Regards
Rajiv
Project Associate
CARE,MIT,
Anna University