How to trim away all extra output from a result using sqlplus

The following code can be put in a shell script and executed by root.

Note the sqlplus directives which will remove all unwanted output from the resulting file /tmp/count_options.out

su - oracle <<!
echo "
set lines 10
set pages 0
set trimspool on
set verify off
set heading off
set feedback off
set echo off
spool /tmp/count_options.out
SELECT TRIM(COUNT(*)) FROM DBA_REGISTRY;
" > /tmp/count_options.sql
sqlplus -s / as sysdba @/tmp/count_options.sql
!

Output is:

 /tmp]# cat count_options.out
4

Note that without the TRIM function, the output will be

/tmp]# cat count_options.out
         4

The -s switch will execute sqlplus silently, without it, the output would be

cat count_options.out
         4
SYS@mydb01>SQL>