Ruby, run linux commands one by one, by SSH and LOG everything

问题

I want to write code in Ruby witch net::ssh that run commands one by one on remote linux machine and log everything (called command, stdout and stderr on linux machine).

So I write function:

  def rs(ssh,cmds)
    cmds.each do |cmd|
      log.debug "[SSH>] #{cmd}"
      ssh.exec!(cmd) do |ch, stream, data|    
        log.debug "[SSH:#{stream}>] #{data}"            
      end  
    end
  end

For example if I want to create on remote linux new folders and file: "./verylongdirname/anotherlongdirname/a.txt", and list files in that direcotry, and find firefox there (which is stupid a little :P) so i call above procedure like that:

Net::SSH.start(host, user, :password => pass) do |ssh|  

  cmds=["mkdir verylongdirname", \                                 #1
        "cd verylongdirname; mkdir anotherlongdirname, \           #2
        "cd verylongdirname/anotherlongdirname; touch a.txt", \    #3
        "cd verylongdirname/anotherlongdirname; ls -la", \         #4
        "cd verylongdirname/anotherlongdirname; find ./ firefox"   #5 that command send error to stderr.
        ]

  rs(ssh,cmds)   # HERE we call our function

  ssh.loop
end

After run code above i will have full LOG witch informations about executions commands in line #1,#2,#3,#4,#5. The problem is that state on linux, between execude commands from cmds array, is not saved (so I must repeat "cd" statement before run proper command). And I'm not satisfy with that.

My purpose is to have cmds tables like that:

  cmds=["mkdir verylongdirname", \     #1
        "cd verylongdirname", \        
        "mkdir anotherlongdirname", \  #2
        "cd anotherlongdirname", \
        "touch a.txt", \               #3
        "ls -la", \                    #4
        "find ./ firefox"]             #5

As you see, te state between run each command is save on the linux machine (and we don't need repeat apropriate "cd" statement before run proper command). How to change "rs(ssh,cmds)" procedure to do it and LOG EVERYTHING (comand,stdout,stdin) like before?

回答1:

Perhaps try it with an ssh channel instead to open a remote shell. That should preserve state between your commands as the connection will be kept open:

http://net-ssh.github.com/ssh/v1/chapter-5.html

Here's also an article of doing something similar with a little bit different approach:

http://drnicwilliams.com/2006/09/22/remote-shell-with-ruby/

Edit 1:

Ok. I see what you are saying. SyncShell was removed from Net::SSH 2.0. However I found this, which looks like it does pretty much what SyncShell did:

http://net-ssh-telnet.rubyforge.org/

Example:

s = Net::SSH.start(host, user)
t = Net::SSH::Telnet.new("Session" => s, "Prompt" => %r{^myprompt :})
puts t.cmd("cd /tmp")  
puts t.cmd("ls")       # <- Lists contents of /tmp

I.e. Net::SSH::Telnet is synchronous, and preserves state, because it runs in a pty with your remote shell environment. Remember to set the correct prompt detection, otherwise Net::SSH::Telnet will appear to hang once you call it (it's trying to find the prompt).

回答2:

You can use pipe instead:

require "open3"

SERVER = "..."
BASH_PATH = "/bin/bash"

BASH_REMOTE = lambda do |command|
  Open3.popen3("ssh #{SERVER} #{BASH_PATH}") do |stdin, stdout, stderr|
    stdin.puts command
    stdin.close_write
    puts "STDOUT:", stdout.read
    puts "STDERR:", stderr.read
  end
end

BASH_REMOTE["ls /"]
BASH_REMOTE["ls /no_such_file"]

回答3:

Ok, finally with the help of @Casper i get the procedure (maby someone use it):

  # Remote command execution
  # t=net::ssh:telnet, c="command_string"
  def cmd(t,c)    
    first=true
    d=''    
    # We send command via SSH and read output piece by piece (in 'cm' variable)
    t.cmd(c) do |cm|       
      # below we cleaning up output piece (becouse it have strange chars)     
      d << cm.gsub(/\e\].*?\a/,"").gsub(/\e\[.*?m/,"").gsub(/\r/,"")     
      # when we read entire line(composed of many pieces) we write it to log
      if d =~ /(^.*?)\n(.*)$/m
        if first ; 
          # instead of the first line (which has repeated commands) we log commands 'c'
          @log.info "[SSH]>"+c; 
          first=false
        else
          @log.info "[SSH] "+$1; 
        end
        d=$2        
      end      
    end

    # We print lines that were at the end (in last piece)
    d.each_line do |l|
      @log.info "[SSH] "+l.chomp      
    end
  end

And we call it in code:

#!/usr/bin/env ruby

require 'rubygems'

require 'net/ssh'

require 'net/ssh/telnet'

require 'log4r'
...
...
...
Net::SSH.start(host, user, :password => pass) do |ssh|  
  t = Net::SSH::Telnet.new("Session" => ssh)
  cmd(t,"cd /")
  cmd(t,"ls -la")
  cmd(t,"find ./ firefox")  
end

Thanks, bye.