Oracle - What TNS Names file am I using?

Question

Sometimes I get Oracle connection problems because I can\'t figure out which tnsnames.ora file my database client is using.

What\'s the best way to figure this out?

Answer 1

For linux:

$ strace sqlplus -L scott/tiger@orcl 2>&1| grep -i 'open.*tnsnames.ora'

shows something like this:

open("/opt/oracle/product/10.2.0/db_1/network/admin/tnsnames.ora",O_RDONLY)=7

Changing to

$ strace sqlplus -L scott/tiger@orcl 2>&1| grep -i 'tnsnames.ora'

will show all the file paths that are failing.

Answer 2

On my development machine I have three different versions of Oracle client software. I manage the tnsnames.ora file in one of them. In the other two, I have entered in the tnsnames.ora file:

ifile=path_to_tnsnames.ora_file/tnsnames.ora

This way, if for some reason the wrong tnsnames.ora file is used by a client, it will always end up at the up-to-date version.

Answer 3

strace sqlplus -L scott/tiger@orcl helps to find .tnsnames.ora file on /home/oracle to find the file it takes instead of $ORACLE_HOME/network/admin/tnsnames.ora file. Thanks for the posting.

Answer 4

Oracle provides a utility called tnsping:

R:\>tnsping someconnection

TNS Ping Utility for 32-bit Windows: Version 9.0.1.3.1 - Production on 27-AUG-20
08 10:38:07

Copyright (c) 1997 Oracle Corporation.  All rights reserved.

Used parameter files:
C:\Oracle92\network\ADMIN\sqlnet.ora
C:\Oracle92\network\ADMIN\tnsnames.ora

TNS-03505: Failed to resolve name

R:\>


R:\>tnsping entpr01

TNS Ping Utility for 32-bit Windows: Version 9.0.1.3.1 - Production on 27-AUG-20
08 10:39:22

Copyright (c) 1997 Oracle Corporation.  All rights reserved.

Used parameter files:
C:\Oracle92\network\ADMIN\sqlnet.ora
C:\Oracle92\network\ADMIN\tnsnames.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (COMMUNITY = **)
 (PROTOCOL = TCP) (Host = ****) (Port = 1521))) (CONNECT_DATA = (SID = ENTPR0
1)))
OK (40 msec)

R:\>

This should show what file you're using. The utility sits in the Oracle bin directory.

Answer 5

By default, tnsnames.ora is located in the $ORACLE_HOME/network/admin directory on UNIX operating systems and in the ORACLE_HOME\network\admin directory on Windows operating systems. tnsnames.ora can also be stored the following locations:

The directory specified by the TNS_ADMIN environment variable (or registry value)

On UNIX operating systems, the global configuration directory. For example, on the Solaris Operating System, this directory is /var/opt/oracle

If you have multiple ORACLE_HOMES, be aware of which one you are using, as the location of the tnsnames.ora file can vary from one ORACLE_HOME to the next.

For the person who mentioned the TWO_TASK environment variable, that is used to set a default database service name to connect to (which could be a database on another server). The service name you set TWO_TASK to is then looked up in the tnsnames.ora file when you connect.

Answer 6

The easiest way is probably to check the PATH environment variable of the process that is connecting to the database. Most likely the tnsnames.ora file is in first Oracle bin directory in path..\network\admin. TNS_ADMIN environment variable or value in registry (for the current Oracle home) may override this.

Using filemon like suggested by others will also do the trick.