IPC

[Yannick Turgeon]

Finally, I decided to telnet the localhost from the localhost and start and
interact with the program from the telnet session. Don't know why I didn't
think to this before.

Maybe I should start another thread but when I get the text from the
interaction between python and telnet session, there are a lot of formating
(probably) characters. Here is the beginning of the text returned by the
telnet session to python:
---------------
Microsoft (R) Windows (TM) Version 5.00 (Build 2195)

Welcome to Microsoft Telnet Service

Telnet Server Build 5.00.99206.1

login:
yannick

password:
***********===========================================================
====                Welcome to Microsoft Telnet Server.
*===============================================================
C:\>


[13;1H
[4;
----------------

I removed them using regexp but I'm wondering if there is something I should
know to prevent them to appear.

Yannick

PS. Yes, I looked with envy to Pexpect yesterday!


<brianc at temple.edu> wrote in message
news:mailman.880.1091030642.5135.python-list at python.org...
> Unfortunately your problem seems to be very specific to the
> application you are trying to communicate with. You can only
> read from the stdout if the program has actually written to
> it. Sometimes programs won't execute until EOF has been reached.
>
> I was reading the Pexpect project this morning as someone
> posted a link to it in reply to your original request. There
> is a good bit there explaining about the pitfalls of working
> with interactive programs.
>
> Sorry I can't be of much more help. Trying to reverse engineer
> the program is probably the only way you'll be able to acheive
> your goal.
>
> -Brian
>
> ---- Original message ----
> >Date: Wed, 28 Jul 2004 11:39:43 -0400
> >From: "Yannick Turgeon" <nobody at nowhere.com>
> >Subject: Re: IPC
> >To: python-list at python.org
> >
> >Thanks Brian for your help.
> >
> >It seems to have something fundamental that I don't
> understand. I've
> >installed process.py (first link) and it's almost doing what
> I want. The
> >problem is that I cannot read stdout before closing stdin.
> How come? Aren't
> >they fully independant? I try to read only one byte at a time
> and it's
> >waiting that byte forever. As if the child process did not
> receive the
> >income data yet to process it. I did execute stdin.flush().
> So I suppose the
> >process received the command ("?\n" in ftp program) and
> produce the output,
> >but I cannot read it.
> >
> >An alternative that I thought about, is to close the stdin in
> order to read
> >stdout and the recreate the stdin for this process. Is that
> faisible? I've
> >got the PID, I should be able to create a pipe with the stdin
> of that
> >process.
> >
> >I haven't been able to make your solution with select.select
> work. After
> >looking to the doc, it's specified that this function can be
> use only with
> >socket when running on Windows. The second link don't work
> for Windows
> >neither.
> >
> >Any feedback would be appreciate.
> >
> >Yannick
> >
> >
> ><brianc at temple.edu> wrote in message
> >news:mailman.856.1090955408.5135.python-list at python.org...
> >> There's two modules that I like to use for this kind of stuff:
> >> http://starship.python.net/crew/tmick/ (process.py)
> >> http://www.lysator.liu.se/~astrand/popen5/ (also process.py
> >> just to be confusing)
> >>
> >> Hopefully one of these will make it into the standard library.
> >> I honestly like them both and combine parts from both when I
> >> need to create my own classes.
> >>
> >> The reason your program hangs is because .readlines() will
> >> keep reading untill an EOF(ie: program exits) is reached and
> >> since the pipe is still open it never will be. (The example
> >> given in the popen2 module,
> >> http://docs.python.org/lib/popen2-flow-control.html, eludes to
> >> this but never actually says it.)
> >>
> >> I recently did a quick hack using select and popen2, but I
> >> doubt it's fast or even safe, but it works.
> >>
> >> #yadda yadda
> >> r, w, e = popen2.popen3(cmd)
> >> cmd = "?\n"
> >> w.write(cmd)
> >> w.flush()
> >> #continuely test for output to read
> >> while select.select([e],[],[],1)[0]:#timeout guessing game
> >>     line=e.readline()
> >>     #do something with line
> >> while select.select([r],[],[],1)[0]:#timeout guessing game
> >>     line=r.readline()
> >>     #do something with line
> >>
> >> If you're output is line buffered you probably shouldn't have
> >> many problems with this approach if you can be assured your
> >> program will respond within the 1 second alloted to it. If
> >> you're positive you'll get output, just remove the timeout.
> >>
> >> Hope this helps.
> >>
> >> -Brian
> >>
> >>
> >> ---- Original message ----
> >> >Date: Tue, 27 Jul 2004 14:20:19 -0400
> >> >From: "Yannick Turgeon" <nobody at nowhere.com>
> >> >Subject: Re: IPC
> >> >To: python-list at python.org
> >> >
> >> >Larry,
> >> >
> >> >As I said, I use FTP only to test the IPC and give here a
> >> known example.
> >> >It's in fact with a custom program that I have to communicate.
> >> >
> >> >Any help in this regard?
> >> >
> >> >Yannick
> >> >
> >> >"Larry Bates" <lbates at swamisoft.com> wrote in message
> >> >news:e9OdnbY0ddteC5vcRVn-sw at comcast.com...
> >> >> Python has built in support for ftp (see ftplib)
> >> >> use it instead of trying to "communicate" with
> >> >> external FTP program.
> >> >>
> >> >> http://www.python.org/doc/current/lib/module-ftplib.html
> >> >>
> >> >> You can catch any exceptions (like failure to connect)
> >> >> by using python try:/except: blocks.
> >> >>
> >> >> HTH,
> >> >> Larry Bates
> >> >> Syscon, Inc.
> >> >>
> >> >> "Yannick Turgeon" <nobody at nowhere.com> wrote in message
> >> >> news:Z6wNc.21572$i_2.899460 at news20.bellglobal.com...
> >> >> > Hi,
> >> >> >
> >> >> > I'm relatively new to Python. I'm using 2.3.4 on W2K.
> >> >> >
> >> >> > What I want to do is to start a program and interact with
> >> it. Say my
> >> >> program
> >> >> > is FTP, I want to start FTP then send the commande "open
> >> x.x.x.x" then
> >> >> look
> >> >> > for the answer (if the connection is opened or not), then
> >> do something
> >> >> > dependant of the success or error.
> >> >> >
> >> >> > I tried with popen3. The problem I got with this: it
> >> seems that I have
> >> >to
> >> >> > end the program before being able to read the output. Or
> >> maybe I'm not
> >> >> using
> >> >> > it correctly. I do test the communication with FTP exec.
> >> but it will be
> >> >a
> >> >> > custom program in real. Here is my code:
> >> >> >
> >> >> >
> >> >> >     def test(self):
> >> >> >         cmd = "ftp"
> >> >> >         r, w, e = popen2.popen3(cmd)
> >> >> >
> >> >> >         cmd = "?\n"            # A simple FTP commande
> >> >> >         w.write(cmd)
> >> >> >         w.flush()
> >> >> >
> >> >> >         # That is what I would like but it's hanging
> >> here. I have to
> >> >> remove
> >> >> > this group and read at the end.
> >> >> >         for line in e.readlines():
> >> >> >             # Do something conditionnal to the result of
> >> "line"
> >> >> >             pass
> >> >> >         for line in r.readlines():
> >> >> >             # Do something conditionnal to the result of
> >> "line"
> >> >> >             pass
> >> >> >
> >> >> >
> >> >> >         cmd = "quit\n"
> >> >> >         w.write(cmd)
> >> >> >         w.flush()
> >> >> >
> >> >> >         for line in e.readlines():
> >> >> >             print line
> >> >> >         for line in r.readlines():
> >> >> >             print line
> >> >> >
> >> >> >         w.close()
> >> >> >         r.close()
> >> >> >         e.close()
> >> >> > ----------------------
> >> >> >
> >> >> > Anybody can help? Thanks for your time.
> >> >> >
> >> >> > Yannick
> >> >> >
> >> >> >
> >> >>
> >> >>
> >> >
> >> >
> >> >--
> >> >http://mail.python.org/mailman/listinfo/python-list
> >
> >
> >--
> >http://mail.python.org/mailman/listinfo/python-list