Odd quirk with xargs and telnet Post: 302458127

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Top Forums UNIX for Dummies Questions & Answers Odd quirk with xargs and telnet Post 302458127 by treesloth on Wednesday 29th of September 2010 07:49:01 PM

09-29-2010

Registered User

Odd quirk with xargs and telnet

For a variety of strange reasons, I've set up an arrangement by which a server responds with "Hi there" if I connect on a specified port. This is a typical transaction:

Code:

# telnet example.com 3334
Trying 123.456.789.101...
Connected to example.com.
Escape character is '^]'.
Hi there
Connection closed by foreign host.

Now, I'm trying to use a quick and dirty way to do this concurrently, using xarg's -P (or max-procs, in some cases) option. Once this works, I'll increase the seq value, add -P concurrency, and be happy. The problem, though, is that I can't get the server's response to show up. Here's a trivial case:

Code:

# seq 1 | xargs -I DISCARD telnet example.com 3334
Trying 123.456.789.101...
Connected to example.com.
Escape character is '^]'.
Connection closed by foreign host.

So, the "1" should be discarded, as there is no DISCARD string in the command called by xargs, and the telnet command should be run. But, this trivial case should be the same thing as just running the telnet command alone since it's wrapped up in a negligible xargs. But, for some reason, the server's "Hi there" doesn't appear. Any idea why that is? I've tried redirecting stderr to stdout on the chance that it's some oddity in the way xargs handles errors, but no luck. I've also placed the telnet command into a little one-liner script and called that instead, without changing the output. Any suggestions? I've scratched my head many times. It didn't help... Many thanks in advance.

Last edited by treesloth; 09-29-2010 at 09:18 PM..

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LEARN ABOUT OSX

regexp::common::uri::telnet

Regexp::Common::URI::telnet(3)				User Contributed Perl Documentation			    Regexp::Common::URI::telnet(3)

NAME

       Regexp::Common::URI::telnet -- Returns a pattern for telnet URIs.

SYNOPSIS

	   use Regexp::Common qw /URI/;

	   while (<>) {
	       /$RE{URI}{telnet}/	and  print "Contains a telnet URI.
";
	   }

DESCRIPTION

   $RE{URI}{telnet}
       Returns a pattern that matches telnet URIs, as defined by RFC 1738.  Telnet URIs have the form:

	   "telnet:" "//" [ user [ ":" password ] "@" ] host [ ":" port ] [ "/" ]

       Under "{-keep}", the following are returned:

       $1  The complete URI.

       $2  The scheme.

       $3  The username:password combo, or just the username if there is no password.

       $4  The username, if given.

       $5  The password, if given.

       $6  The host:port combo, or just the host if there's no port.

       $7  The host.

       $8  The port, if given.

       $9  The trailing slash, if any.

REFERENCES

       [RFC 1738]
	   Berners-Lee, Tim, Masinter, L., McCahill, M.: Uniform Resource Locators (URL). December 1994.

SEE ALSO

       Regexp::Common::URI for other supported URIs.

AUTHOR

       Damian Conway (damian@conway.org)

MAINTAINANCE

       This package is maintained by Abigail (regexp-common@abigail.be).

BUGS AND IRRITATIONS

       Bound to be plenty.

LICENSE and COPYRIGHT
       This software is Copyright (c) 2001 - 2009, Damian Conway and Abigail.

       This module is free software, and maybe used under any of the following licenses:

	1) The Perl Artistic License.	  See the file COPYRIGHT.AL.
	2) The Perl Artistic License 2.0. See the file COPYRIGHT.AL2.
	3) The BSD Licence.		  See the file COPYRIGHT.BSD.
	4) The MIT Licence.		  See the file COPYRIGHT.MIT.

perl v5.16.2							    2010-02-23					    Regexp::Common::URI::telnet(3)