When I start the Onmonitor program and run Status, I receive the message, "Unable to attach to shared memory." But I have Informix 7.23 for AIX!
What's going on?
Check to see that your database is running. If it's not, start it with Onmonitor | Mode | Startup. Do a ps -elf to see if you have multiple "oninit" processes running. If not, your database is not running.
If it is running, make sure that your environment variables are set correctly. You need INFORMIXSERVER to be set to the proper machine. Check with a "known good" login. Try logging in as Informix and seeing if it works. If it works as Informix, you have a problem with your environment. See your DBA.