lane@dalcs.UUCP (John Wright/Dr. Pat Lane) (12/13/88)
Hello. A few months back, I remember seeing some discussion on how a
program could modify the environment of the program which executed it
(or, were it is different, of the initial command processor). Now
that the question has come up for me and I've tried it and seen it's
not so simple...Now, I wish I'd read the discussion. Can someone tell
what the upshot was or provide me with any articles they saved?
I know that both the environment segment and the parent's PSP segment
are stored in the PSP. Using this you could trace back to the parent
program or all the way back to the first program loaded after booting
(COMMAND.COM usually). Then, it's easy to find the environment of that
program. The catch, as I see it, is that if the parent program is
COMMAND.COM, the copy of the environment that it passes to its children
is not its own environment but an allocated memory block after the program.
If you want to set an environment variable in a program run from COMMAND.COM
that will be seen by other programs run from the same shell or a sub-shell,
then you would have to modify the allocated memory block, no?
How can you tell in a consistant way if the parent program is COMMAND.COM
or a program using a similar way of handling the environment. What about
other command processors that might do something else in this regard?
Thanks.
--
John Wright ///////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
Cdn/Bitnet: lane@cs.dal.cdn Arpa: lane%dalcs.uucp@uunet.uu.net
Uucp: lane@dalcs.uucp or {uunet,watmath,utai}!dalcs!lane
--
John Wright ///////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
Cdn/Bitnet: lane@cs.dal.cdn Arpa: lane%dalcs.uucp@uunet.uu.net
Uucp: lane@dalcs.uucp or {uunet,watmath,utai}!dalcs!lane lane@dalcs.UUCP (John Wright/Dr. Pat Lane) (01/13/89)
Hello. A few months back, I remember seeing some discussion on how a
program could modify the environment of the program which executed it
(or, were it is different, of the initial command processor). Now
that the question has come up for me and I've tried it and seen it's
not so simple...Now, I wish I'd read the discussion. Can someone tell
what the upshot was or provide me with any articles they saved?
I know that both the environment segment and the parent's PSP segment
are stored in the PSP. Using this you could trace back to the parent
program or all the way back to the first program loaded after booting
(COMMAND.COM usually). Then, it's easy to find the environment of that
program. The catch, as I see it, is that if the parent program is
COMMAND.COM, the copy of the environment that it passes to its children
is not its own environment but an allocated memory block after the program.
If you want to set an environment variable in a program run from COMMAND.COM
that will be seen by other programs run from the same shell or a sub-shell,
then you would have to modify the allocated memory block, no?
How can you tell in a consistant way if the parent program is COMMAND.COM
or a program using a similar way of handling the environment. What about
other command processors that might do something else in this regard?
Thanks.
--
John Wright ///////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
Cdn/Bitnet: lane@cs.dal.cdn Arpa: lane%dalcs.uucp@uunet.uu.net
Uucp: lane@dalcs.uucp or {uunet,watmath,utai}!dalcs!lane