Oracle environment variables and identifiers that you don't pay much attention

Oracle environment variables and identifiers that you don't pay much attention
Sign (?) Represents the ORACLE_HOME Environment Variable
Eg:
SQL> ALTER TABLESPACE TEMP ADD DATAFILE '? /Dbs/temp02.dbf 'size 200 M;


Sign (@) represents the ORACLE_SID environment variable
Eg:
SQL> ALTER TABLESPACE tablespace_name ADD DATAFILE tempfile @. dbf


------ Oracle software running environment variables
-- ORACLE_TRACE tracks shell script execution during installation. The principle is to set-x implicitly.


ORACLE_TRACE = T enable shell Tracing
ORACLE_TRACE = if it is set to null, no trace is performed.


-- TNS_ADMIN oracle net service configuration file, it seems that many people do not know this variable. Sometimes the listening management exception means that this variable is not properly set,
Eg:

TNS_ADMIN = $ ORACLE_HOME/network/admin



-- TWO_TASK specifies the default connection ID (which must be configured in tnsnames. ora). If this variable is set, you can quickly connect to the database:

TWO_TASK = lixora

SQL> CONNECT lixora
Enter password: lixora


---------- Unix environment variables
-- CLASSPATH Used with Java applications

CLASSPATH = $ ORACLE_HOME/JRE/lib: $ ORACLE_HOME/jlib/* no default settings. The following settings must be included */

-- PATH Used by the shell to locate executable programs; shel uses this variable to determine the executable program
Eg:
PATH =/bin:/usr/local/bin:/usr/bin/X11: $ ORACLE_HOME/bin: $ HOME/bin: