Call DSPMSGD with the message ID of the message to see a specific one, or just DSPMSGD RANGE(*FIRST *LAST) to see all possible messages. Is that what you mean?
System error messages should by default go to QSYSOPR message queue, so if you are wanting to see actual errors which are occurring, monitor that queue. Other program messages may only go to the user who generated the error, unless specifically coded to send elsewhere.
Does that help?
Dear i want to show all messages??
I think how do you define critical?
because the message might be critical to me and not to you..