In bash/shell:
[bash]sqlplus /nolog #just log onto sqlplus console
connect as sysdba #connect as sysdba and prompt for login
connect user/passw as sysdba #log-in as a sysdba with user | default: system/manager[/bash]

In <bash><sql>:
[sql]startup –startup a database
shutdown –shutdown a database
exit –disconnect from sqlplus
SELECT * FROM NLS_SESSION_PARAMETERS; –query nls_lang params of session user
SELECT * FROM NLS_DATABASE_PARAMETERS; –query nls_lang params of database user