I have been asked today to check a database performance issue of an Oracle 11.2.0.3.
The vendor doesn’t want to give me a Linux access and only provided me a temporary database access as a sysdba.
No problem, I can check the content of alert log file as a part of the troubleshoot querying sys.x$dbgalertext fixed table.

SQL> SELECT originating_timestamp, message_text
FROM sys.x$dbgalertext
WHERE originating_timestamp > SYSDATE - 7
and message_text LIKE '%ORA%'
ORDER BY originating_timestamp DESC;

ORIGINATING_TIMESTAMP                                                            MESSAGE_TEXT
-------------------------------------------------------------------------------- --------------------------------------------------------------------------------
16/02/15 08:58:22,468 -05:00                                                     Non critical error ORA-48913 caught while writing to trace file "/jv01/app/oracl
                                                                                 Error message: ORA-48913: Writing into trace file failed, file size limit [0] re
                                                                                 Writing to the above trace file is disabled for now on...
16/02/15 08:51:10,557 -05:00                                                     Non critical error ORA-48913 caught while writing to trace file "/jv01/app/oracl
                                                                                 Error message: ORA-48913: Writing into trace file failed, file size limit [0] re
                                                                                 Writing to the above trace file is disabled for now on...
16/02/15 08:41:00,360 -05:00                                                     Non critical error ORA-48913 caught while writing to trace file "/jv01/app/oracl
                                                                                 Error message: ORA-48913: Writing into trace file failed, file size limit [0] re
                                                                                 Writing to the above trace file is disabled for now on...
16/02/15 08:07:56,386 -05:00                                                     Non critical error ORA-48913 caught while writing to trace file "/jv01/app/oracl
                                                                                 Error message: ORA-48913: Writing into trace file failed, file size limit [0] re
                                                                                 Writing to the above trace file is disabled for now on...
16/02/15 08:07:15,850 -05:00                                                     Non critical error ORA-48913 caught while writing to trace file "/jv01/app/oracl
                                                                                 Error message: ORA-48913: Writing into trace file failed, file size limit [0] re
                                                                                 Writing to the above trace file is disabled for now on...
16/02/15 08:02:35,292 -05:00                                                     WARNING: inbound connection timed out (ORA-3136)
16/02/15 08:02:35,235 -05:00                                                     WARNING: inbound connection timed out (ORA-3136)
16/02/15 08:02:34,774 -05:00                                                     WARNING: inbound connection timed out (ORA-3136)

Or I can run the following query also:

select inst_id, originating_timestamp, message_text
  from TABLE(gv$(cursor (select inst_id, originating_timestamp, message_text
                    from v$diag_alert_ext
                   where originating_timestamp > (sysdate - 7)
                     and message_text like '%ORA-%')))
 order by inst_id, originating_timestamp;

Also I wanted to check without asking the provider about the OS hosting the database instance;
This can be done using the following query;

SQL> select dbms_utility.port_string from dual;

PORT_STRING

x86_64/Linux 2.4.xx

As you can see it is Linux x86_64.
enjoy!