How to Check Oracle Version?

we can find oracle database installed version from two way . see follow

1) From inside oracle

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a) CMD> sqlplus /nolog

b) SQL> SELECT * FROM v$version ;

C) SQL> SELECT VERSION FROM v$instance;

d) SQL> select * from product_component_version;

2) from OS

a)

G:\app\Administrator\product\11.1.0\db_1\OPatch> set Oracle_home=G:\app\Administrator\product\11.1.0\db_1

G:\app\Administrator\product\11.1.0\db_1\OPatch>opatch lsinventory

B) $ORACLE_HOME/bin/svrmgrl command=exit | grep "Release"

c) $ORACLE_HOME/bin/oracle | grep NLSRTL

d) from “sqlnet.log’ file .