Identify a specific environment Oracle variable to connect a remote Oracle database ?

Good evening
I nned your help pls, In an unix server i want to connect to a remote oracle databse server by sqlplus.

I tried to find out the user/passwd and service name by env variable and all Ive got is this:

ORACLE_SID_REPCOL=SCL_REPCOL
ORACLE_SID=xmeta
ORACLE_SID_TOL=SCL_PROTOLCOL
ORACLE_SID_SCL=SCL_PROCOL

$ echo $USERBD_REPCOL
preportes
$ echo $ORACLE_SID_REPCOL
SCL_REPCOL
$ echo $PASSBD_REPCOL
REPCOL_07

In the oracle env vars i cant find neither SID_ORACLE, USER AND PASSWD, but in the application server which is Datastage automatically connects to the remote oracle database sever, and print out these variables but the password is encrypted:

orclRmngPswd=HD;@A;VIM93M0O4I<KJ4CK04BL<MDCU4CUB=kO:dG1U?3
orclRmngSID=ROAMING
orclRmngUser=sql_datastage

The 1st question is why the aplication itself does connect to orclRmngSID=ROAMING withs its own user/passwd but these variables are not defined in the env variables ?

2. dont know if has something related to dblink, that is comonly used to connect to database

Thanks for your help in advanced

Not sure what you are seeing.

This is a complete oracle connect string for sqlplus:

sqlplus username/password@oracle_instance

The parts are
username - valid oracle user name for the instance
password - we have encrypted our passwords in the files, scripts and variables used to call
sqlplus scripts like pl/sql. They password is decrypted on the fly, so it never appear anywhere for prying eyes.
instance - there must be a tnsnames.ora file in a special directory that specifies the instances and how to connect to them, sometimes there are also aliases for instances.

If you define the ORACLE_SID variable all is does is to remove the need for specifying the instance.

If you need to get in to oracle, contact your DBA for help, the way you are going will not get you far. If you are root on the system, then there are ways to connect to oracle as the sysdba user by becoming the oracle on the server that runs the database and
use connect / as sysdba in sqlplus.

The real question with your limited level of oracle knowledge is: why are you trying to get logged in without going the usual way -> your manager clears it & DBA sets up your account?

ok, thanks you very much for your explanation which made me understand things i didnt know

i use the usual way: sqlplus username/password@oracle_instance

The application itself uses scripts and variables to connect to the oracle instance orclRmngSID=ROAMING and it really does , but i dont understand where the variables user, passwd, oracle_instance are getting from since these variables are not set in env unix enviroment var ? is it not suppossed those variables shoul be set in the env variable ?
Thanks for your help