sql query - create replace function

Hi all,

I created a script to install postgresql. One of the steps is to run a sql
query.

the problem is that i need to run the query as postgres user, plus it needs
to be at psql shell prompt command line, i.e:

# from your shell prompt enter:
$ psql <dbname>

# From the psql prompt enter the follow plpgsql code to create the
bitfromint4 function:

$ create or replace function bitfromint4 (integer) returns bit varying as '
begin return $1::bit(32); end;' language 'plpgsql' immutable strict;

#Exit psql:
$ \q

I expected something like
su - postgres -c "pgsql dbname && create or replace function bitfromint4
(integer) returns bit varying as ' begin return $1::bit(32); end;' language
'plpgsql' immutable str\
ict;"

but i see when the script runs "pgsql dbname" the bash script looses control
of the process, and there's no way back, from pgql shell prompt when it gets
in, to continue the script

iuri