#EM-SSH Em-ssh is a net-ssh adapter for EventMachine. For the most part you can take any net-ssh code you have and run it in the EventMachine reactor.

Em-ssh is not associated with the Jamis Buck's net-ssh library. Please report any bugs with em-ssh to https://github.com/simulacre/em-ssh/issues ##Installation gem install em-ssh

##Synopsis

EM.run do
  EM::Ssh.start(host, user, :password => password) do |connection|
    connection.errback do |err|
      $stderr.puts "#{err} (#{err.class})"
    end
    connection.callback do |ssh|
      # capture all stderr and stdout output from a remote process
      ssh.exec!('uname -a').tap {|r| puts "\nuname: #{r}"}
    
      # capture only stdout matching a particular pattern
      stdout = ""
      ssh.exec!("ls -l /home") do |channel, stream, data|
        stdout << data if stream == :stdout
      end
      puts "\n#{stdout}"
    
      # run multiple processes in parallel to completion
      ssh.exec('ping -c 1 www.google.com')
      ssh.exec('ping -c 1 www.yahoo.com')
      ssh.exec('ping -c 1 www.rakuten.co.jp')
    
      #open a new channel and configure a minimal set of callbacks, then wait for the channel to finishes (closees).
      channel = ssh.open_channel do |ch|
        ch.exec "/usr/local/bin/ruby /path/to/file.rb" do |ch, success|
          raise "could not execute command" unless success
    
          # "on_data" is called when the process writes something to stdout
          ch.on_data do |c, data|
            $stdout.print data
          end
        
          # "on_extended_data" is called when the process writes something to stderr
          ch.on_extended_data do |c, type, data|
            $stderr.print data
          end
        
          ch.on_close { puts "done!" }
        end
      end
    
      channel.wait

      ssh.close
      EM.stop
    end
  end
end

See http://net-ssh.github.com/ssh/v2/api/index.html

##Shell

Em-ssh provides an expect-like shell abstraction layer on top of net-ssh in EM::Ssh::Shell

Example

require 'em-ssh/shell'
EM.run do
  EM::Ssh::Shell.new(host, ENV['USER'], "") do |shell|
    shell.callback do
      shell.expect('~]$ ')
      shell.expect('~]$ ','uname -a')
      shell.expect('~]$ ')
      shell.expect('~]$ ', '/sbin/ifconfig -a')
      EM.stop
    end
    shell.errback do
      puts "error: #{err} (#{err.class})" 
      EM.stop
    end
  end
end

Run Multiple Commands in Parallel

require 'em-ssh/shell'
EM.run do
  EM::Ssh::Shell.new(host, ENV['USER'], '') do |shell|
    shell.errback do |err|
      puts "error: #{err} (#{err.class})"
      EM.stop
    end 

    shell.callback do 
      commands.clone.each do |command|
        mys = shell.split # provides a second session over the same connection
        mys.on(:closed) do
          commands.delete(command)
          EM.stop if commands.empty?
        end

        puts("waiting for: #{waitstr.inspect}")
        # When given a block, Shell#expect does not 'block'
        mys.expect(waitstr) do 
          puts "sending #{command.inspect} and waiting for #{waitstr.inspect}"
          mys.expect(waitstr, command) do |result|
            puts "#{mys} result: '#{result}'"
            mys.close
          end 
        end 
      end 
    end 
  end 
end 

Other Examples

See bin/em-ssh for an example of a basic replacement for system ssh.

See bin/em-ssh-shell for a more complex example usage of Shell.

Known Issues

Em-ssh relies on Fibers. MRI 1.9.2-p290 on OSX Lion has been known to segfault when using Fibers.

##Copyright Copyright (c) 2011 Caleb Crane

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Portions of this software are Copyright (c) 2008 Jamis Buck