SQL*Plus: Release 18.104.22.168.0 Production on Mon May 20 12:26:29 2013
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SQL> startup ;
ORA-00000: normal, successful completion
you need to investigate more about this error most the cause for this error :
1- Oracle Home contain "/" in the end of detestation.
2- if one not works for you, Then you need to check your networks included with listener