Getting Started - Oracle RMAN for Absolute Beginners - page 5

If your Linux/Unix account is a member of the dba group (your shop might use a different group name, but dba
is the most common), you can connect to your database with the required privileges via SQL*Plus by virtue of being
logged in to your Linux/Unix account.
On Windows, the OS user must be part of either the ora_dba group or the ora_oper group. In Windows
environments, you can verify which OS users belong to the ora_dba group as follows: select Control Panel ➤
Administrative Tools ➤ Computer Management ➤ Local Users and Groups ➤ Groups. You should see a group named
something like ora_dba . You can click that group and view which OS users are assigned to it. Additionally, for OS
authentication to work in Windows environments, you must have the following entry in your sqlnet.ora file: SQLNET.
AUTHENTICATION_SERVICES=(NTS) .
On Linux/Unix, you can quickly verify the operating system groups that your account belongs to using the id
command without any parameters:

$ id
uid=500(oracle) gid=500(oinstall) groups=500(oinstall),501(dba),502(oper),503(asmdba),
504(asmoper),505(asmadmin),506(backupdba)

The prior output indicates that the oracle user is included in several groups, one of which is dba . Any user who
belongs to the dba group can connect to the database with SYSDBA privileges. A user with SYSDBA privileges can start
and stop the database. This example uses OS authentication to connect to your database as the user SYS :

$ sqlplus / as sysdba

No username or password is required when using OS authentication (hence just the slash without a user/
password) because Oracle first checks to see if the OS user is a member of a privileged OS group, and if so, connects
without checking the username/password. You can verify that you have connected as SYS by issuing the following:

SQL> show user
USER is "SYS"

The privileged OS groups are established when installing the Oracle software. There are a few OS groups that
pertain to backup and recovery:

•

dba

•

oper

backupdba (available starting with Oracle 12c)
Each OS group corresponds to certain database privileges. Table 1-1 shows the mapping of OS groups to database
system privileges and operations.

•

Table 1-1. Mapping of OS Groups to Privileges Related to Backup and Recovery

Operating System Group Database System Privilege Authorized Operations

dba sysdba Start up, shut down, alter database, create and drop database,

toggle archivelog mode, back up, and recover database.

oinstall none Install and upgrade Oracle binaries.

oper sysoper

Start up, shut down, alter database, toggle archivelog
mode, back up, and recover database.

backupdba sysbackup Available starting with Oracle 12 c , this privilege allows

you to start up, shut down, and perform all backup and
recovery operations.