Please bear with me as the Question i am goin to ask me sound silly. I get the following error when i run the SQLLDR command on a Unix box. The SQLLDr command syntax is correct, yet i get the below error: "SQL Loader errror output: Message 2100 not found; No message file for product=RDBMS, facility=ULMessage 2100 not found; No message file for product=RDBMS, facility=UL". If i google on this error it indicates that some Oracle environment variables like ORACLE_HOME, ORACLE_SID. I have 2 questions regarding this: 1. How can i check what the ORACLE_HOME, ORACLE_SID variable values on Unix. if i echo on these variables it displays blank 2. My SQLLDR command is something like this /usr/local/oracleclient-9i-64/bin/sqlldr userid=testdev/testdev01@O02TST0 control=/usr/local/ccms/tst//jclass/properties//aval.ctl ..... As you see "O02TST0" is the HostName i am trying to connect to. How would SQLLDR resolve the HostName? Will it look in tsnnames.ora file to resolve it? If that is the case, then where is the tnsnames.ora file typically located on Unix?