<p>We are trying to duplicate one of our informix database on a test server, but without Informix expertise in house we can only guess what we need to do.  I am learning this stuff on the fly myself and nowhere near the expertise level needed to operate Informix efficiently or even inefficiently.  Anyhow...
We managed to copy the .dat and .idx files from the live server somewhere.  Installed Linux and the latest Informix Dynamic Server on it and have it up and running.  </p>

<p>Now what should we do with the .dat and idx files from the live server?  Do we copy it somewhere and it will recognize it automatically?</p>

<p>Or is there an equivalent way like you can do attach DB from MS SQLServer to register the database files in the new database?</p>

<p>At my rope end...</p>

I don't have any Informix-specific advice but for situations like this you can usually find the answer by looking up how to move a database (a common admin task, and usually well described in the manual) and just skipping the steps that would remove the old database.
Also, be careful of problems caused by different system architectures; some DBs fail spectacularly if you move them from a big-endian system (such as Solaris) to a little-endian system (such as x86 Linux)  Again, the manual section on moving a DB would cover any extra steps that are needed.