如何查看oracle是否启动

可以通过以下步骤来查看Oracle是否启动：

1. 打开命令行窗口或终端。
2. 输入命令`lsnrctl status`，回车执行。
3. 如果Oracle已经启动，命令行输出会显示类似以下信息：

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 01-JAN-2019 00:00:00

Copyright (c) 1991, 2010, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date                01-JAN-2019 00:00:00
Uptime                    0 days 0 hr. 1 min. 12 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
Listener Log File         /u01/app/oracle/diag/tnslsnr/localhost/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=1521)))
Services Summary...
Service "ORCL" has 1 instance(s).
  Instance "ORCL", status READY, has 1 handler(s) for this service...
The command completed successfully

其中重点查看 "STATUS of the LISTENER" 一段，如果显示 "Ready" ，则说明Oracle已经启动。

4. 如果Oracle没有启动，命令行输出会显示类似以下信息：

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 01-JAN-2019 00:00:00

Copyright (c) 1991, 2010, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))
TNS-12541: TNS:no listener
 TNS-12560: TNS:protocol adapter error
  TNS-00511: No listener
   Linux Error: 111: Connection refused

其中重点查看 "TNS-12541: TNS:no listener" 一行，如果显示这个错误，则说明Oracle没有启动。