How to view the database alert log file _oracle

1, view the operating system version
Sql> select * from V$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0-prod
Pl/sql Release 10.2.0.1.0-production
CORE 10.2.0.1.0 Production
TNS for Linux:version 10.2.0.1.0-production
Nlsrtl Version 10.2.0.1.0-production
Sql>

2. View the location of the alert log file (Alert_sid.log)
Sql> Show parameter Dump
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
Background_core_dump string Partial
Background_dump_dest String/u01/oracle/admin/bdump
Core_dump_dest String/u01/oracle/admin/cdump
Max_dump_file_size string 10240
Shadow_core_dump string Partial
User_dump_dest String/u01/oracle/admin/udump

3. Create directory Alert
Note: directory is not an entity, just a point pointing to a path in the OS
sql> Create or Replace directory alert as '/u01/oracle/admin/bdump ';
Directory created.
Sql>

4. Create External Table alert
Sql> CREATE TABLE Alert
1 (log varchar2 (1000))
2 Organization External
3 (Type Oracle_loader
4 Default directory Alert
5 Access Parameters
6 (Records delimited by newline)
7 location (' Alert_prod.log '))
8 Reject limit unlimited;
Table created.

5. View the contents of alert
Sql> SELECT * from alert where rownum<20;
LOG
--------------------------------------------------------------------------------------------------------------- -----------------------------------------------------------------------------------------
Wed Feb 27 11:05:11 2013
Starting ORACLE instance (normal)
Cannot determine all dependent dynamic libraries For/proc/self/exe
Unable to find dynamic library libocr10.so in search paths
Rpath =/ade/aime1_build2101/oracle/has/lib/:/ade/aime1_build2101/oracle/lib/:/ade/aime1_build2101/oracle/has/ lib/:
Ld_library_path is not set!
The default library directories Are/lib And/usr/lib
Unable to find dynamic library libocrb10.so in search paths
Unable to find dynamic library libocrutl10.so in search paths
Unable to find dynamic library libocrutl10.so in search paths
license_max_session = 0
license_sessions_warning = 0
Picked Latch-free SCN Scheme 2
Using log_archive_dest_1 parameter Default value As/u01/oracle/product/10.2.0/db_1/dbs/arch
Autotune of undo retention is turned on.
Imode=br
Ilat =10
License_max_users = 0
SYS Auditing is disabled
Rows selected.
Sql>

6, look at the database of what lovely ora-mistakes it
Sql> SELECT * from alert where log like '%ora-% ';
LOG
--------------------------------------------------------------------------------------------------------------- -----------------------------------------------------------------------------------------
ORA-959 signalled During:alter database default tablespace users ...
ORA-959 signalled During:drop tablespace uses ...
ORA-12919 signalled During:drop tablespace users ...
ORA-1549 signalled During:drop tablespace users ...
ORA-1505 signalled During:alter database add logfile Group 1
ORA-1184 signalled During:alter database add logfile Group 1
ORA-1013 signalled During:alter tablespace TTS Read only ...
ORA-1013 signalled During:alter tablespace TTS Read only ...
ORA-1013 signalled during:alter tablespace users Read Only ...
ORA-1539 signalled during:alter tablespace users Read Only ...