$ su oracle
bash-3.2$ . /usr/lib/oracle/xe/app/oracle/product/10.2.0/server/bin/oracle_env.sh
bash-3.2$ sqlplus /nolog
$ connect / as sysdba
$ shutdown immediate
$ startup mount
$ alter database archivelog;
$ alter database open;
$ SELECT LOG_MODE FROM SYS.V$DATABASE; ARCHIVELOG
$ quit