leland@dragonfly.wri.com (12/09/90)
It seems that one of the public domain programs I compiled under
10.2 behaves differently under 10.3. The program is mush (the mail users
shell). Since I not know how signals are supposed to work under bsd, posix,
sysv, etc. this description may well be incomplete.
Apparently, much sets up a handler for sigchld. When it forks to
collect and ship the message, this child sets its tty group to -1 and
resets all signals. The parent then does a wait3 for the child to terminate.
Under 10.2, the child would terminate and the parent would return. Under 10.3,
when the child would terminate, so would the parent. The result of all this is
that if I used mush to reply to any of my mail, the program would terminate!
To simple force it to work, I made mush simply ignore sigchld, but this has
other effects that are undesirable.
If anyone could come up with insight as to signal incompatibilities between
10.2 and 10.3, specifically this kind of problem, I would appreciate a reply.
Leland Ray
Systems Administrator -- Unix platforms
WRI, Inc.
(217) 398-0700
leland@wri.com