Linguists are the common name for translators and interpreters, however, lawyer-linguists are considered as specialists given their required diploma in law. Linguist exams are announced each year in June or July for different language combinations, but the exam they need to pass is by and large the same as for any other Administrator profile. Linguists are always AD level officials once recruited and they can move to other non-linguistic positions after the initial 2-3 years.
See also:
Auditor, Economist, European Public Administration, Statistician, Interpreter, Lawyer, Financial Policy Officer
Related link:
Tips and Tricks, EU Agency Selection and Recruitment Database