I'm creating a script that would generate an actual backup script.
I have to give this script to our clients and I don't know in advance
where init.ora will be located on client site.
So to find path and copy init.ora file during database hot backup
I use this query:

select 'host copy '||value||' &&BACKUP_TS_PATH'
from v$parameter where name='ifile'

Most of the time it works, but I notice that on some of the servers this query:

select value from v$parameter where name='ifile'

returns NULL.

I was wondering if anybody has some workaround to find init.ora path
dynamically to copy init.ora together with data files backup.