From: Jamis Buck <jamis_buck@...>
Date: 2005-02-18T00:38:37+09:00
Subject: Re: net::ssh popen3 issue?

On 00:09 Fri 18 Feb     , ritchie@ipowerhouse.com wrote:
> hi
> 
> I'm using popen3 to query a database. I'm returning 20 records but I'm
> only getting 5 back. The command executed is a simple psql query to a
> pg database so there's not much room for error there. Is there some
> kind of timeout or fixed buffer size when using popen3? Thanks for any
> help.
> 
> Here's some relevant code:
> 
>     records = []
> 	headings = []
> 	Commands.session.process.popen3( "sudo bin/get_account" ) { |i,o,e|
> 
>   		x = o.read
> 		puts x
> 		lines = x.split("\n")
> 
> 		lines.each_with_index { |l,i|
> 			fields = l.split("|")
> 			if i == 0
> 				headings = fields
> 			else
> 				if i != 1  # got a line
> 					records << fields
> 				end
> 			end
> 			#puts "line #{i}, fields #{records}"
> 		}
> 		puts "number of lines is #{lines.length}"
> 	}   
> 	  
> 	tw = headings.length 
> 	th = records.length

It sounds like it might be a timing issue... there are a lot of those
when using the Net::SSH stuff, unfortunately.

Perhaps try using the shell.sync service to do it:

  shell = session.shell.sync

  result = shell.send_command "sudo bin/get_account"
  lines = result.stdout
  ...

The asynchronous nature of Net::SSH really wreaks havoc with these
kinds of things. The shell.sync service is probably the most robust
way I've seen for executing remote commands via ssh, but even it still
suffers from some weak areas. If anyone has come up with a clever way
to execute remote commands using Net::SSH, I'd love to hear about
them.

- Jamis

-- 
Jamis Buck
jamis_buck@byu.edu
http://jamis.jamisbuck.org
------------------------------
"I am Victor of Borge. You will be assimil-nine-ed."