今天在虚拟机中测试用alert文件来构造初始化参数文件，步骤如下：
1 找到alert文件
通常alert文件在bdump目录下，如果不知道bdump目录在哪，可以在sqlplus下，用命令来查看
SQL> show parameter background_dump_dest
NAME TYPE VALUE------------------------------------ ----------- ------------------------------background_dump_dest string /opt/oracle/admin/orcl/bdump
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拷贝日志文件中关键参数文件并修改，命名为$/ORACLE_HOME/dbs/pfileabc.ora
processes = 150 shared_pool_size = 88080384 large_pool_size = 4194304 java_pool_size = 4194304 streams_pool_size = 0 sga_target = 281018368 control_files = ('/opt/oracle/oradata/orcl/control01.ctl','/opt/oracle/oradata/orcl/control02.ctl','/opt/oracle/oradata/orcl/control03.ctl') db_block_size = 8192 __db_cache_size = 180355072 compatible = 10.2.0.1.0 db_file_multiblock_read_count= 16 db_recovery_file_dest = '/opt/oracle//flash_recovery_area' db_recovery_file_dest_size= 2147483648 undo_management = AUTO undo_tablespace = UNDOTBS1 remote_login_passwordfile= EXCLUSIVE db_domain = '' dispatchers = '(PROTOCOL=TCP) (SERVICE=orclXDB)' job_queue_processes = 10 background_dump_dest = '/opt/oracle/admin/orcl/bdump' user_dump_dest = '/opt/oracle/admin/orcl/udump' core_dump_dest = '/opt/oracle/admin/orcl/cdump' audit_file_dest = '/opt/oracle/admin/orcl/adump' db_name = 'orcl' open_cursors = 300 pga_aggregate_target = 92274688
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2 关闭数据库并用新的参数文件启动
SQL> shutdown immediateDatabase closed.Database dismounted.ORACLE instance shut down.SQL> startup pfile=$ORACLE_HOME/dbs/pfileabc.oraORACLE instance started.
Total System Global Area 281018368 bytesFixed Size 1218968 bytesVariable Size 96470632 bytesDatabase Buffers 180355072 bytesRedo Buffers 2973696 bytesDatabase mounted.Database opened.
