First, are you sure it's a database? AIX supports sequential files and various types of ISAM files. If it is a database, you need to determine what it is. You'll need privileges to do that, or need to work with a Unix admin. Start looking for certain keywords like (duh) oracle, sybase, db2, ibm, informix, cincom, supra, datacom, ingres, etc. After you find the type of database, you need to determine if the database is currently running. Then you can start thinking about access.
Stupid questions - Have you asked the questions you've asked us to anyone else at the job? Is there a central repository for documentation? Are there any ODBC or Data Sources connections on your PC, or anyone else's PC?
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Sometimes the grass is greener on the other side because there is more manure there - original.