passing query result to script

[JDoyle]

This is probably pretty basic, but it defies me.
I want to write a script which selects the segment ID of the active rollback segment based on:
select usn from v$rollstat where xacts >0
and then pass the result on to the following query:
select * from dba_rollback_segs where segment_id = (result from above query).
What are my options here?

Many thanks in advance.

Johnny D.

[marist89]

select * from dba_rollback_segs where segment_id in (select usn from v$rollstat where xacts >0 )