[oracle@12cr2db ~]$ sqlplus / as sysbda

SQL*Plus: Release 12.2.0.1.0 Production

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Use SQL*Plus to execute SQL, PL/SQL and SQL*Plus statements.

Usage 1: sqlplus -H | -V

    -H             Displays the SQL*Plus version and the
                   usage help.
    -V             Displays the SQL*Plus version.

Usage 2: sqlplus [ [<option>] [{logon | /nolog}] [<start>] ]

  <option> is: [-AC] [-C <version>] [-L] [-M "<options>"] [-NOLOGINTIME] [-R <level>]
               [-S]

    -AC            Enable Application Continuity.
    -C <version>   Sets the compatibility of affected commands to the
                   version specified by <version>.  The version has
                   the form "x.y[.z]".  For example, -C 10.2.0
    -L             Attempts to log on just once, instead of
                   reprompting on error.
    -M "<options>" Sets automatic HTML or CSV markup of output.  The options
                   have the form:
                   {HTML html_options|CSV csv_options}
                   See SQL*Plus User's Guide for detailed HTML and CSV options.
    -NOLOGINTIME   Don't display Last Successful Login Time.
    -R <level>     Sets restricted mode to disable SQL*Plus commands
                   that interact with the file system.  The level can
                   be 1, 2 or 3.  The most restrictive is -R 3 which
                   disables all user commands interacting with the
                   file system.
    -S             Sets silent mode which suppresses the display of
                   the SQL*Plus banner, prompts, and echoing of
                   commands.

  <logon> is: {<username>[/<password>][@<connect_identifier>] | / }
              [AS {SYSDBA | SYSOPER | SYSASM | SYSBACKUP | SYSDG | SYSKM | SYSRAC}] [EDITION=value]

    Specifies the database account username, password and connect
    identifier for the database connection.  Without a connect
    identifier, SQL*Plus connects to the default database.

    The AS SYSDBA, AS SYSOPER, AS SYSASM, AS SYSBACKUP, AS SYSDG,
    AS SYSKM and AS SYSRAC options are database administration privileges.

    <connect_identifier> can be in the form of Net Service Name
    or Easy Connect.

      @[<net_service_name> | [//]Host[:Port]/<service_name>]

        <net_service_name> is a simple name for a service that resolves
        to a connect descriptor.

        Example: Connect to database using Net Service Name and the
                 database net service name is ORCL.

           sqlplus myusername/mypassword@ORCL

        Host specifies the host name or IP address of the database
        server computer.

        Port specifies the listening port on the database server.

        <service_name> specifies the service name of the database you
        want to access.

        Example: Connect to database using Easy Connect and the
                 Service name is ORCL.

           sqlplus myusername/mypassword@Host/ORCL

    The /NOLOG option starts SQL*Plus without connecting to a
    database.

    The EDITION specifies the value for Session Edition.


  <start> is: @<URL>|<filename>[.<ext>] [<parameter> ...]

    Runs the specified SQL*Plus script from a web server (URL) or the
    local file system (filename.ext) with specified parameters that
    will be assigned to substitution variables in the script.

When SQL*Plus starts, and after CONNECT commands, the site profile
(e.g. $ORACLE_HOME/sqlplus/admin/glogin.sql) and the user profile
(e.g. login.sql in the working directory) are run.  The files may
contain SQL*Plus commands.

Refer to the SQL*Plus User's Guide and Reference for more information.