I had to run nid (also known as dbnewid) on a database as part of a test refresh at the weekend. This changes the dbid of the database.
Out of sheer laziness I ran it from with sqlplus by using the ‘!’ host command feature.
Nid, quite understandablly doesn’t really like this – it hangs.
I ctrl-c’d it, exited to the OS and re-ran and it worked fine.
The 10g doc for nid is here: http://download.oracle.com/docs/cd/B19306_01/server.102/b14215/dbnewid.htm