rman ORA-01031 RMAN-00554 from command line after connecting AS SYSBACKUP

The way of connecting to database by rman from command line and from the script is a little bit different (the difference is in connection string).

For example, for operating system command line use '"..."' form :

$ rman  target '"c##ddi@orcl2 as sysbackup"' 

For the script use '...' form

RMAN> connect target 'c##ddi@orcl2 as sysbackup'

P.S. For channels configuration use '"..."' form.