expectperl-discuss

[Expectperl-discuss] Having problems with prompt

[amit1017 <gos...@ho...>]

Hi guys,

I am new to perl and expect.  I started putting a script together that
telnets into desired devices one at a time and runs specified commands. 
Problem I have is, that the prompt on this hosts does not follow a certain
norm.  Some prompts are in caps, some are in lower caps.  Normally, prompts
are device names, but in some case our device names exceeds the number of
characters allowed in the hostname, so it cuts of the exceeded letters.  So
having the following doesn't really work at times:

$telnet->expect($timeout, "$HostName");

Is there anyway, I can do this.  That once I spawn the telnet session and
log in.  The prompt that it gets, it stores it into a variable and than I
can leverage that variable throughout my script wherever it expects a
prompt.

Also, these devices are all cisco devices.  Is there a recommended timeout
values? I have $telnet->exp_internal(1) in my script.  So In middle of the
output after a command is run, I see several /r's.  Thanks in advance for
your help.

Amit.
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Re: [Expectperl-discuss] Having problems with prompt

[Bradford R. <bri...@po...>]

I spent a long time (longer than I should have) trying to come up with the
perfect solution for this, but it's a tough one because there are lots of
unexpected situations that can get in the way and leave your script hanging
becuase it either missed something that didn't fit your regexp or
misinterpreted some extra output as a prompt.

In general, I found the easiest and most reliable solution was to try to
have your script autodetect the prompt under the assumption that it would be
the last line of text after you enter your password.  If you can manage to
autodetect it reliably, then you can use in subsequent expect() calls rather
than a regular expression.

You just have to make sure your script waits long enough after sending the
password before it tries to detect the prompt... sometimes there's a hiccup
during login and the prompt takes a half-second or so to be sent, and if
there's any preceeding output such as a motd/banner the script might grab
that instead.

It's a good thing that these are all cisco devices, so the output should be
more consistent and predictable than on unix boxes.

Good luck.
-- Brad

On 11/2/07, amit1017 <gos...@ho...> wrote:
>
>
> Hi guys,
>
> I am new to perl and expect.  I started putting a script together that
> telnets into desired devices one at a time and runs specified commands.
> Problem I have is, that the prompt on this hosts does not follow a certain
> norm.  Some prompts are in caps, some are in lower caps.  Normally,
> prompts
> are device names, but in some case our device names exceeds the number of
> characters allowed in the hostname, so it cuts of the exceeded
> letters.  So
> having the following doesn't really work at times:
>
> $telnet->expect($timeout, "$HostName");
>
> Is there anyway, I can do this.  That once I spawn the telnet session and
> log in.  The prompt that it gets, it stores it into a variable and than I
> can leverage that variable throughout my script wherever it expects a
> prompt.
>
> Also, these devices are all cisco devices.  Is there a recommended timeout
> values? I have $telnet->exp_internal(1) in my script.  So In middle of the
> output after a command is run, I see several /r's.  Thanks in advance for
> your help.
>
> Amit.
> --
> View this message in context:
> http://www.nabble.com/Having-problems-with-prompt-tf4737304.html#a13547267
> Sent from the Perl - Expectperl-Discuss mailing list archive at Nabble.com
> .
>
>
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Re: [Expectperl-discuss] Having problems with prompt

[Bradford R. <bt...@po...>]

I spent a long time (longer than I should have) trying to come up with the
perfect solution for this, but it's a tough one because there are lots of
unexpected situations that can get in the way and leave your script hanging
becuase it either missed something that didn't fit your regexp or
misinterpreted some extra output as a prompt.

In general, I found the easiest and most reliable solution was to try to
have your script autodetect the prompt under the assumption that it would be
the last line of text after you enter your password.  If you can manage to
autodetect it reliably, then you can use in subsequent expect() calls rather
than a regular expression.

You just have to make sure your script waits long enough after sending the
password before it tries to detect the prompt... sometimes there's a hiccup
during login and the prompt takes a half-second or so to be sent, and if
there's any preceeding output such as a motd/banner the script might grab
that instead.

It's a good thing that these are all cisco devices, so the output should be
more consistent and predictable than on unix boxes.

Good luck.
-- Brad


On 11/2/07, amit1017 <gos...@ho...> wrote:
>
>
> Hi guys,
>
> I am new to perl and expect.  I started putting a script together that
> telnets into desired devices one at a time and runs specified commands.
> Problem I have is, that the prompt on this hosts does not follow a certain
> norm.  Some prompts are in caps, some are in lower caps.  Normally,
> prompts
> are device names, but in some case our device names exceeds the number of
> characters allowed in the hostname, so it cuts of the exceeded
> letters.  So
> having the following doesn't really work at times:
>
> $telnet->expect($timeout, "$HostName");
>
> Is there anyway, I can do this.  That once I spawn the telnet session and
> log in.  The prompt that it gets, it stores it into a variable and than I
> can leverage that variable throughout my script wherever it expects a
> prompt.
>
> Also, these devices are all cisco devices.  Is there a recommended timeout
> values? I have $telnet->exp_internal(1) in my script.  So In middle of the
> output after a command is run, I see several /r's.  Thanks in advance for
> your help.
>
> Amit.
> --
> View this message in context:
> http://www.nabble.com/Having-problems-with-prompt-tf4737304.html#a13547267
> Sent from the Perl - Expectperl-Discuss mailing list archive at Nabble.com
> .
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Splunk Inc.
> Still grepping through log files to find problems?  Stop.
> Now Search log events and configuration files using AJAX and a browser.
> Download your FREE copy of Splunk now >> http://get.splunk.com/
> _______________________________________________
> Expectperl-discuss mailing list
> Exp...@li...
> https://lists.sourceforge.net/lists/listinfo/expectperl-discuss
>

Re: [Expectperl-discuss] Having problems with prompt

[Ian M. <iw...@do...>]

>
>
>Hi guys,
>
>I am new to perl and expect.  I started putting a script together that
>telnets into desired devices one at a time and runs specified commands. 
>Problem I have is, that the prompt on this hosts does not follow a certain
>norm.  Some prompts are in caps, some are in lower caps.  Normally, prompts
>are device names, but in some case our device names exceeds the number of
>characters allowed in the hostname, so it cuts of the exceeded letters.  So
>having the following doesn't really work at times:
>
>$telnet->expect($timeout, "$HostName");
>
>Is there anyway, I can do this.  That once I spawn the telnet session and
>log in.  The prompt that it gets, it stores it into a variable and than I
>can leverage that variable throughout my script wherever it expects a
>prompt.
>
>Also, these devices are all cisco devices.  Is there a recommended timeout
>values? I have $telnet->exp_internal(1) in my script.  So In middle of the
>output after a command is run, I see several /r's.  Thanks in advance for
>your help.
>
>Amit.
>-- 
>View this message in context: http://www.nabble.com/Having-problems-with-prompt-tf4737304.html#a13547267
>Sent from the Perl - Expectperl-Discuss mailing list archive at Nabble.com.
>
>
>-------------------------------------------------------------------------
>This SF.net email is sponsored by: Splunk Inc.
>Still grepping through log files to find problems?  Stop.
>Now Search log events and configuration files using AJAX and a browser.
>Download your FREE copy of Splunk now >> http://get.splunk.com/
>_______________________________________________
>Expectperl-discuss mailing list
>Exp...@li...
>https://lists.sourceforge.net/lists/listinfo/expectperl-discuss
>

I have found when  using expect with a   linux shell that various characters but mostly carriage return
are inserted in output lines. I realised that the shell was wrapping long lines and was in  edit mode,
where some input characters cause extra output as part of the line editing.

Perhaps if you could tell your telnet and  cisco shell to use as long a line as possible  and use
what my telnet manual calls old telnet line by line, where only complete lines are to the the remote host
then no extra characters are returned.

    Ian W Moor                  Department of Computing,
iw...@do...           Imperial College.
                                    180 Queensgate
                                     London SW7 2AZ UK.