I think the text interface tools you are thinking of would be dbaccess.
Their load/unload tools also rock in that they are fast and real easy to learn and run ( dbunload/dbload ).
I especially like the ability to just unload delimited data via plain 'ol sql....much easier than Oracle's SQL*Plus
where you use spool and get just more of the same ugly output, or sqlldr which requires a control file.
my main beef with informix is that it takes a supreme being to get DBD/DBI compiled with
imho, IBM buying informix is a good thing if you are a customer, IBM rarely orphans paying customers. and if
Lotus is an indicator, Informix folks will be around long past their relevence in the industry. :-)