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Re: [newbie] trying socket as a replacement for nc

References <efae1b3c-c9c5-4ef4-8e94-7fbe8716ab53@googlegroups.com>
Date 2013-12-11 15:20 -0800
Subject Re: [newbie] trying socket as a replacement for nc
From Dan Stromberg <drsalists@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.3939.1386804043.18130.python-list@python.org> (permalink)

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On Wed, Dec 11, 2013 at 3:08 PM, Jean Dubois <jeandubois314@gmail.com>wrote:

> I have an ethernet-rs232 adapter which allows me to connect to a
> measurement instrument by means of netcat on a linux system.
> e.g. entering nc 10.128.59.63 7000
> allows me to enter e.g.
> *IDN?
> after which I get an identification string of the measurement instrument
> back.
> I thought I could accomplish the same using the python module "socket"
> and tried out the sample program below which doesn't work however:
>

Sockets reserve the right to split one socket.send() into multiple
socket.recv()'s on the other end of the communication, or to aggregate
multiple socket.send()'s into a single socket.recv() - pretty much any way
the relevant IP stacks and communications equipment feel like for the sake
of performance or reliability.

The confusing thing about this is, it won't be done on every transmission -
in fact, it'll probably happen rather seldom unless you're on a heavy
loaded network or have some MTU issues (see Path MTU Discovery, and bear in
mind that paths can change during a TCP session).  But writing your code
assuming it will never happen is a bad idea.

For this reason, I wrote
http://stromberg.dnsalias.org/~strombrg/bufsock.html , which abstracts away
these complications, and actually makes things pretty simple.  There are
examples on the web page.

HTH

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Thread

[newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-11 15:08 -0800
  Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-11 15:20 -0800
    Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 00:28 -0800
      Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-12 13:23 -0800
        Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 19:23 -0800
          Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-12 19:32 -0800
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-13 03:03 -0800
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-13 03:56 -0800
          Re: [newbie] trying socket as a replacement for nc Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-13 08:35 +0000
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-13 04:20 -0800
              Re: [newbie] trying socket as a replacement for nc rusi <rustompmody@gmail.com> - 2013-12-13 09:04 -0800
              Re: [newbie] trying socket as a replacement for nc rusi <rustompmody@gmail.com> - 2013-12-13 09:09 -0800
                Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-14 05:11 -0800
            Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-14 05:14 -0800
              Re: [newbie] trying socket as a replacement for nc Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-14 13:29 +0000
        Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-16 01:40 -0800
          Re: [newbie] trying socket as a replacement for nc Ervin Hegedüs <airween@gmail.com> - 2013-12-16 11:04 +0100
    Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-12 14:16 +0000
      Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-13 01:23 +1100
      Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-12 13:27 -0800
        Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-13 16:06 +0000
          Re: [newbie] trying socket as a replacement for nc Dan Stromberg <drsalists@gmail.com> - 2013-12-14 17:24 -0800
            Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-15 15:15 +0000
              Re: [newbie] trying socket as a replacement for nc Roy Smith <roy@panix.com> - 2013-12-15 10:51 -0500
                Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-16 03:04 +1100
                Re: [newbie] trying socket as a replacement for nc Roy Smith <roy@panix.com> - 2013-12-15 12:44 -0500
                Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-15 22:42 +0000
                Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-16 09:48 +1100
      Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-13 08:58 +1100
        Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-13 16:10 +0000
          Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-14 03:19 +1100
            Re: [newbie] trying socket as a replacement for nc Grant Edwards <invalid@invalid.invalid> - 2013-12-13 16:57 +0000
              Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-14 04:05 +1100
        Re: [newbie] trying socket as a replacement for nc 88888 Dihedral <dihedral88888@gmail.com> - 2013-12-16 04:38 -0800
          Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-16 23:59 +1100
          Re: [newbie] trying socket as a replacement for nc Roy Smith <roy@panix.com> - 2013-12-16 09:03 -0500
            Re: [newbie] trying socket as a replacement for nc 88888 Dihedral <dihedral88888@gmail.com> - 2013-12-18 23:20 -0800
      Re: [newbie] trying socket as a replacement for nc Dave Angel <davea@davea.name> - 2013-12-12 19:52 -0500
  Re: [newbie] trying socket as a replacement for nc Conor Hughes <conorh@conorh.net> - 2013-12-11 15:38 -0800
    Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 00:08 -0800
      Re: [newbie] trying socket as a replacement for nc Chris Angelico <rosuav@gmail.com> - 2013-12-12 19:21 +1100
        Re: [newbie] trying socket as a replacement for nc Jean Dubois <jeandubois314@gmail.com> - 2013-12-12 01:21 -0800
          Re: [newbie] trying socket as a replacement for nc Alister <alister.ware@ntlworld.com> - 2013-12-12 14:05 +0000
          Re: [newbie] trying socket as a replacement for nc Alister <alister.ware@ntlworld.com> - 2013-12-12 14:05 +0000
            Re: [newbie] trying socket as a replacement for nc Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-12 14:34 +0000
  Re: [newbie] trying socket as a replacement for nc Christian Gollwitzer <auriocus@gmx.de> - 2013-12-13 00:43 +0100

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