>Craig commented on Randy Medd noticing the following:
>
>>While in QEDIT, I thought I'd see how the Posix tail program worked
>>with the '-f' option.  I entered:
>>
>>        /:tail.hpbin.sys "-f ./FILE"
>>
>>tail dutifully displayed the last 10 lines and stopped, waiting for
>>more records from ./FILE.  I then typed control-Y and got an END OF
>>PROGRAM message - because QEDIT terminated, not just tail.
>>Feature?  Bug?
>
>I too tried this and was able to reproduce your results.  ...
>So, in answer to your question, it seems like a bug to me.
 
Seemed like one to me too, but after trying on three occasions to get
the Response Center to acknowledge this (call ids w3180671, w3198149
and w3198498 back in November '94), I finally gave up.
 
The bottom line is that applications are expected to arm the appropriate
Posix signal handlers for the SIGINT signal (which is what's generated
when a Posix application sees <Control-Y>), and that there's nothing
anyone can do (at least under MPE/iX 5.0) to prevent the SIGINT from
propagating to all processes in the process tree.
 
As an example: from the CI I run QEDIT, within QEDIT I run MPEX, and within
MPEX I run TAIL.HPBIN.SYS and hit <Control-Y>.  MPEX (version 25) contains
the approprate SIGINT signal handlers, so it catches the SIGINT as TAIL
terminates, and allows you to continue entering MPEX commands.  But, as
soon as you exit MPEX, you're back to the ':' prompt again, without QEDIT.
 
It seemed ridiculous to me that all process-handling applications should
have to add SIGINT handlers to work-around this 'feature', but it also
seems that there's no easy way for SIGINT to have been implemented in a
Posix-compliant manner without having this side-effect.
 
Someone from the labs would have to comment on whether future MPE/iX
releases will allow applications to block propagation of SIGINT to
other processes.
 
Paul Taffel
VESOFT Development Staff      (310) 282 0420
 
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