Oracle Database Discussions

I am not able startup a database in nomount state for particular ORACLE_SID. It seems it doesn't like the ORACLE_SID I set to.
It's throwing following error
ORA-07345: The datafile name must not contain the string '..'.

Steps I did like follows
1) export ORACLE_SID=ABC
2) I have init.ora, which has DB_NAME=ABC
3) startup nomount pfile='/export/home/oracle/init.ora'

It works great and puts db in nomount state

But, when I change ORACLE_SID=XYZ and edited init.ora with
DB_NAME=XYZ, then did
startup nomount pfile=''/export/home/oracle/init.ora', then it throws following error

ORA-07345: The datafile name must not contain the string '..'.