A bit late to the party, but one reason why this might not be working is that your shell may be stripping the quotes so that sqlplus
never sees them. Though if that were the case, I would have thought using '"..."'
would have worked...
Even still, have you tried escaping the quotes with \
? i.e.,
sqlplus -S -L USER/\"+oS0pocWEpvaX++CN3]8nM‘2eX\"@host @script.sql