select * from v$log; --look at the current log
select * from v$logfile; -- look at the logfile for the current log

exec sys.dbms_logmnr.add_logfile('/home/oracle/oradata/tiny/redo01.log')
exec sys.dbms_logmnr_d.build('yonglogmnr.ora','/home/oracle/oracle/dbs')
--if doesn't work (maybe due to utl_file_dir not set there), change /home/oracle/oracle/dbs to /tmp
exec sys.dbms_logmnr.start_logmnr(dictfilename => '/home/oracle/oracle/dbs/yonglogmnr.ora')
select max(scn) from v$logmnr_contents;
select sql_redo from v$logmnr_contents where scn > [a number close to max(scn)];
exec sys.dbms_logmnr.end_logmnr