Resore PG-Data from Files after crash

Hi!

I've the following Problem and hope someone can help me. My PostgreSQL
Database were running on a Debian Linux. Some day the OS crahsed and -
here's the Problem - there is no dump file from Database. But I still
have the files in base, global, pg_clog. So I did a fresh setup and
copied the files in the pg data directory. But even I try to start via
pg_ctl fails caus:

Starting PostgreSQL database server: postmaster(FAILED)
ERROR: There is no PostgreSQL database framework in /srv/postgres/data.
Run initdb as the postgres user to create it

I don't want to run initDB because the dir isn't empty - of course I
copied my old data files in there.

What can I do?

Thank you!!

Christian Meier