Re: telnet from spawned telnet process
- From: David Gravereaux <davygrvy@xxxxxxxxx>
- Date: Sat, 26 May 2007 10:16:36 -0700
Thanks for the response. Sorry to have repeated an often asked
question. I had looked online for help and did not see anything
(after your response I did go and look and find your posting).
I should make a form letter with inserts :)
Your question about Expect for Windows (E4W) can be answered with this form letter
as this question comes up about once a week in this newsgroup. Please try the
I don't suppose you have any other idea?
Does the process that you spawn, then create new processes that you want Expect to
trap as well? I'm not sure if that aspect works right. I know that if you spawn
cmd.exe then ask it to start a process, expect won't grab the output from the new
process. I'm not sure why that doesn't work, but I'm sure it is fixable.
Who's going to fix it is the big question. Even though the source for it is open,
no one seems to assist with its development.
The big problem with E4W is its lack of a X-platform test suite.. It only works
on Unix, or most are skipped on win due to system differences which ever your
perspective. For example, the 'od' command does not exist on windows. Nor are
any windows specific tests contained in it, such as the shell problem. Thinking
to the future toward a working [interact] command, the test suite would need to be
rather large to make sure all Console APIs are properly "copied" to the user
console and would require lots of C-based exercises.
It wouldn't be so bad if the technique of trapping console output on windows
wasn't so damn complicated. The feature to do it does not exist in the OS the way
it does on Unix. IOW, it forces what is not expressed as a stream into one. I
wouldn't call what E4W does a hack job, but it comes close. I was even tempted to
try a technique called 'Detours', which is similar in concept but uses import
table memory rewriting rather than setting breakpoints with the system debugger
for redirection. 'Detours' would probably be more efficient, but I didn't think
Microsoft's license agreement was friendly enough.
PS. I give myself to permission to insult E4W, should it be warranted for the
conversation, because I wrote it. IOW, I adapted Gordon Chaffee's old 1996 work
into the modern code base a couple years ago. I had to make very deep and drastic
changes to allow a generic/platform split. I pulled out enough hair to make a wig.
PPS. don't get me started on Tcl's channel API ;)
Calvin : I think we have got enough information now, don't you?
Hobbes : All we have is one "fact" that you made up.
Calvin : That's plenty. By the time we add an introduction, a few
illustrations and a conclusion, it'll look like a graduate thesis.
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