sqlplus登录报错如下：

Copyright © 1982, 2009, Oracle. All rights reserved.

ERROR:
ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux-x86_64 Error: 2: No such file or directory
Process ID: 0
Session ID: 0 Serial number: 0

重启大法

$ sqlplus /nolog

SQL*Plus: Release 11.2.0.1.0 Production on Fri May 14 16:11:04 2021

Copyright © 1982, 2009, Oracle. All rights reserved.

SP2-0640: Not connected
SQL> conn / as sysdba
Connected to an idle instance.
*
ERROR at line 1:
ORA-01034: ORACLE not available
Process ID: 0
Session ID: 0 Serial number: 0

SQL> shutdown abort
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area 2.6189E+10 bytes
Fixed Size 2213856 bytes
Variable Size 1.3153E+10 bytes
Database Buffers 1.2885E+10 bytes
Redo Buffers 148766720 bytes
Database mounted.
Database opened.
SQL> conn test/test12352
Connected.