prompt> /usr/local/bin/pgbash              --- Start Pgbash as sub-shell
pgbash> connect to db2@xxx.com user sakaida;  --- connect to db2
pgbash> connect to db3@yyy.com user postgres; --- connect to db3
        .......
pgbash> set connection db2;                   --- sets db2 as current DB
pgbash> addr='OSAKA'                               
pgbash> insert into test values(              --- new line
>  111,'name',
> '$addr'                                     --- use a shell valiable
> ); 

pgbash> select * from test limit 100; | more  --- pipeline
        .......
pgbash> select * from test; > /tmp/sel.dat &  --- redirect + background_Job
pgbash> cat /tmp/sel.dat
        .......
pgbash> set connection db3;                   --- sets db3 as current DB
pgbash> select * from test limit 100; | more  
        .......
pgbash> fc select                             --- edit and execute a Select
        .......
pgbash> !!                                    --- re-execute a Select
        .......
pgbash> disconnect all;                       
pgbash> exit                                 --- end of Pgbash
prompt>

  #!/usr/local/bin/pgbash
  connect to dbname2 as db2 user postgres; 
  begin;
  declare cur cursor for select * from test; 
  while [ 1 ]
  do
     fetch in cur into :AA :AA_IND, :BB;        --- sets shell variables
     if [ $SQLCODE -eq $SQL_NOT_FOUND ]; then   --- end of a Fetch
        break
     fi
     if [ $SQLCODE -eq $SQL_OK ]; then          --- normal end
        if [ $AA_IND -ne $SQL_NULL ]; then      --- AA is not NULL
           echo "$AA, $BB"
        fi
     fi 
  done
  end;
  disconnect db2;

  Here, $SQL shell variables are reserved.
  $SQLCODE       --- status parameter
  $SQL_OK        --- NORMAL END code value
  $SQL_NOT_FOUND --- NOT FOUND code value
  $SQL_NULL      --- NULL code value