C:\exp '/as sysdba' full=y file=ds.dmp
Export: Release 10.1.0.2.0 - Production on Sat Mar 19 16:42:34 2005
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EXP-00004: invalid username or password
Username: / as sysdba
EXP-00008: ORACLE error 1219 encountered
ORA-01219: database not open: queries allowed on fixed tables/views only
EXP-00000: Export terminated unsuccessfully
It is common knowledge, (at least it should be) that export / import will only work when DB is open. If you want to restrict users while exporting/ importing , startup your database in resticted more and run exp/imp as an user with restrict access privilege granted.
One, who thinks that the other one who thinks that know and does not know, does not know either!
If you are worried about other sessions changing data while it is being exported, then specify consistent=y, which changes the export session's transaction isolation level to a read-only serializable mode.