there are a lot of posts around concerning the different credentials syntax for sysdba logins between sqlplus and impdp/expdp. in most cases people get stuck upon the fact, that the usual double quote syntax, they know from sqlplus:
sqlplus "/ as sysdba"
ceases to work for impdp/expdp like so:
expdp "/ as sysdba" directory=data_pump_dir ... LRM-00108: Unzulõssiger Wert des Positionsparameters 'sysdba'
ok, we all learned that impdp/expdp prefer a single quote syntax for tea time:
expdp '/ as sysdba' directory=data_pump_dir ...
on unix system shells even escaped by \.
expdp \'/ as sysdba\' directory=data_pump_dir ...
however, the introdution of windows powershell:
PS C:\Users> cmd Microsoft Windows [Version 6.1.7600] Copyright (c) 2009 Microsoft Corporation. Alle Rechte vorbehalten.
found me learning another variant of the syntax game. because windows powershell uses a diffenrent approach of interpreting empty spaces on command lines, you have to enclose all the unnamed (credentials) and named (all the rest) switches of impdp/expdp into additional double quotes.
impdp "'/ as sysdba' directory=data_pump_dir ..."
last but not least, do not forget that employing sys for impdp/expdp may deliver inconsistent data over a multiple of transactions, since sys cannot and shall not do a transaction level consisent read (read-only transaction). this is especially important for partitioned or nested tables.