Path: utzoo!utgpu!water!watmath!clyde!bellcore!faline!ulysses!allegra!mit-eddie!husc6!cca!mirror!adelie!axiom!insyte!jad
From: jad@insyte.UUCP
Newsgroups: comp.os.vms
Subject: How to get a child process to tell its parent that it died
Keywords: VMS processes c SIGCLD
Message-ID: <125@insyte.uucp>
Date: 15 Jan 88 16:22:13 GMT
Organization: Innovative Systems (INSYTE), Newton, MA
Lines: 34
Posted: Fri Jan 15 11:22:13 1988


We are porting our product from a HP9000 running unix to a
VAX running VMS.  The product is written in c.

The way the product works is that the frontend (the editor, etc)
forks off a child process (which does the real work) and the
two processes talk to each other thru pipes.  All this works fine.

The question is, how can the parent process tell if the child has
died?  If something went wrong and the child dies, unless the
parent knows this, it will hang waiting for input.  In UNIX we use 
the death of child signal.

There seem to be several options in VMS.  The first is to
ask the system if the child process (I have the process id) is 
still alive using LIB$GETJPI before every read or write.
I would assume that this would be slow, but I'm not sure.

The second approach would be to use AST's somehow.  Being new to
VMS I'm not sure how yet.

Since this is a fairly common thing to do, I hope someone out there has
already done it!  I would appreciate any help.  Please remember 
that I am new to VMS so make your responses fairly detailed.

Thanks

Jill Diewald
Innovative Systems
1 Gateway Center Suite 910
Newton, Ma 02158
Phone: 617-965-8450

email: ... /harvard/axiom/insyte/jad