错误现象：
[oracle@wwl data]$ exp "sys/oracle@wwl as sysdba" file=/data/sys.dmp log=/data/sys.log full=y;
LRM-00108: invalid positional parameter value 'as'
EXP-00019: failed to process parameters, type 'EXP HELP=Y' for help
EXP-00000: Export terminated unsuccessfully
原因：
这个可能是Oracle10g的一个BUG，只需按照如下两种方法即可：
解决办法：
第一种方法：
[oracle@wwl data]$ exp \"sys/oracle as sysdba\"
file=/data/sys.dmp log=/data/sys.log full=y;
Export: Release 10.2.0.1.0 - Production on Wed May 2 19:20:12 2012
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses WE8ISO8859P1 character set (possible charset conversion)
About to export the entire database ...
. exporting tablespace definitions
. exporting profiles
. exporting user definitions
. exporting roles
. exporting resource costs
第二种方法：
[oracle@wwl ~]$ exp \'sys/oracle as sysdba\' file=/data/sys1.dmp log=/data/sys1.log full=y;
Export: Release 10.2.0.1.0 - Production on Wed May 2 19:26:08 2012
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses WE8ISO8859P1 character set (possible charset conversion)
About to export the entire database ...
. exporting tablespace definitions^[
. exporting profiles
. exporting user definitions