Informix – Get last executed SQL query

This is my preferred method.

onstat -g ses <sesid>

Where <sesid> is the session id of the connected user querying the database.
To get the session id

onstat -g ses

This will produce output similar to below.

IBM Informix Dynamic Server Version 9.40.FC7     -- On-Line -- Up 4 days 09:44:52 -- 1445712 Kbytes
session                                      #RSAM    total      used       dynamic
id       user     tty      pid      hostname threads  memory     memory     explain
31457    informix -        0        -        0        12288      11368      off
31450    informix -        0        -        0        12288      11368      off

That will print out all the sessions;  from there, use the session id column (column 1) to get the session id and plug it into the first command to show last executed statement.

onstat -g ses 31457

This produced the following output for me

Sess  SQL            Current            Iso Lock       SQL  ISAM F.E.
Id    Stmt type      Database           Lvl Mode       ERR  ERR  Vers Explain
30943 -              v004               CR  Not Wait   0    0    9.03 Off
Last parsed SQL statement :
  select distinct(tmptype) from form_cat