SQL & PL/SQL

OS: Oracle Linux 5.10

DB Oracle 11.2.0

I need to query the database and assign the return value to a shell variable, but it's not working.

create table imr_env (key varchar2(1000), value varchar2(1000) ;
insert into imr_env values('TblspcUsagePct','90');
commit;

Here is the shell script:

#!/bin/bash
echo "in script"
ORACLE_HOME=/u01/app/oracle/product/11.2.0/db_1 ; export ORACLE_HOME
ORACLE_SID=IMR1 ; export ORACLE_SID
export PATH=$PATH:$ORACLE_HOME/bin

pct=`sqlplus -S app/manager <<END
       set serveroutput on
       declare
          output_val number ;
       BEGIN
          select value into output_val from imr_env where key = 'TblspcUsagePct' ;
          dbms_output.put_line('output_val: ' || to_char(output_val)) ;
       END ;
       /
       exit;
END`

## another sqlplus connection, use $pct in the where clause

echo "var value is $pct"

Here is the output:

SQL> ./test.sh
in script
var value is 

output_val: 90

Why isn't the shell variable being populated with the value retrieved from the database?

I need to use $pct in another query that will tablespaces that are at least 90% full.