I need a program / tool to convert an informix database to Postgres.
Can anybody help me?
What version/operating system are you running Informix and PostgreSQL on?
I don't know of any specific tool to do such a conversion, I would expect you will have to export the data from informix with the command 'dbexport <database_name_here>' which will generate a 'tar' file containing separate text files containing the SQL data about *each* Informix table.
You can then convert manually each SQL file to Postgresql data types and then import these changed files into PostgreSQL. This is exactly what I am doing, and I expect it to take more than a week to process fully. Of course it depends a lot on the complexity of the database(s) you are converting. And if the database uses specific features of Informix that PostgreSQL does not have (I don't know it there are any, but I'd expect that there are a few) then it may take a bit of database re-engineering.
It can always be done, just not by someone without a *lot* of patience and time.
If your Informix installation has an ODBC driver, I'd recommend you try to copy all data you need into an Access database, and later transfer that into Postgresql through ODBC also.