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> Really I'm trying to find out an explanation of the mystery ... > I'm suspecting ... sends SIGUSR1 to the processes ... Usually in Unix you can use trap to set a signal to be ignored, and then it will continue to be ignored also by the child process (e.g Progress) started from this process. A specific trap procedure will not be inherited by a child process after the child execs a new program, since the procedure needs to live inside the new process, and that is wiped when the new program is loaded. But the status of being ignored is usually kept, in addition to a few other states that do not require a trap procedure. (See man exec & man fork.) So maybe you can set SIGUSR1 to be ignored before starting Progress, and then see if that stops the actions that you suspect are caused by SIGUSR1. (Unless Progress interferes with this some other way.) On the other hand, if the problem is that you do not see any action caused by SIGUSR1 and are wondering if they are really being received, then I would say like previous respondents that it can not be done by using trap in the parent process. You would have to do something inside the Progress process to set that up. However, if the signal is not reaching the process, one possible cause to look for is whether there is already some startup procedure that is setting this signal up to be ignored, before starting Progress. Also, maybe you could fool the sender of the signal, to send the signal to a wrapper process of your own, where you can trap it, in stead of to the real Progress process. E.g replace the Progress command with a script of your own.
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