title: sqlplus fails to start. wants *.msb files
body: <p>Installed sqlplus from oracle downloads. Unpacked both files
  instantclient-basic-linux.x64-12.1.0.1.0.zip
  instantclient-sqlplus-linux.x64-12.1.0.1.0.zip 
  sqlplus fails to start with this error:</p>
  
  <p>Error 6 initializing SQL*Plus
   SP2-0667: Message file sp1.msb not found
   SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory</p>
  
  <p>I assume I don't have to install the whole oracle server for sql client to run. and basic-linux zip is deemed to be everything you need to run OCI apps which sqlplus is.</p>
  
  <p>Where do I get these .msb files?</p>