You log in, set your ORACLE_SID and ORACLE_HOME and then try to run SQLPLUS. And you get this:
What is going on here? The file exists in the ORACLE_HOME as expected but yet it can’t seem to find it.
Your PATH variable is pointing at an incorrect ORACLE_HOME, likely you are running more than 1 Oracle DB on the box with different homes and the PATH hasn’t been updated with the new ORACLE_HOME so you’ve got a binary mismatch between the ORACLE_HOME and SQLPLUS. Either run SQLPLUS using the full ORACLE_HOME path like:
Or change the PATH and put this ORACLE_HOME at the start.