如何使用Ruby的Net :: SSH库获取退出状态? [英] How to get exit status with Ruby's Net::SSH library?

问题描述

我有一段代码，只是尝试在远程服务器上执行脚本，如果脚本失败，我想进行跟进，想象一下:

I have a snippet of code, simply trying to execute a script on a remote server, in the event that it fails, I'd like to make a follow-up call, imagine this:

require 'rubygems'
require 'net/ssh'
require 'etc'

server = 'localhost'

Net::SSH.start(server, Etc.getlogin) do |ssh|
  puts (ssh.exec("true")  ? 'Exit Success' : "Exit Failure")
  puts (ssh.exec("false") ? 'Exit Success' : "Exit Failure")  
end

我期望(忽略在我为人为的示例中打印的stdout和stderr)-但是第一行应该以0退出，我希望Ruby会以false的形式出现并显示"Exit Failure"(确定，所以逻辑是错误的，三元数需要翻转)-但是第二行应该以相反的状态退出，而事实并非如此.

I would expect (ignoring that stdout and stderr are printed in my contrived example) - but first line should exit with 0 which I would expect Ruby would interperate as false and display "Exit Failure" (sure, so the logic is wrong, the ternary needs to be flipped) - but the second line should exit with the opposite status, and it doesn't.

我什至找不到文档中有关如何执行此操作的信息，我有点担心自己做错了吗?！

I can't even find anything in the documentation about how to do this, and I'm a little worried that I might be doing it wrong?!

推荐答案

我发现使用Net :: SSH运行进程的以下方式更为有用.它为您提供了不同的stdout和stderr，exit code和exit signal.

I find the following way of running processes with Net::SSH much more useful. It provides you with distinct stdout and stderr, exit code and exit signal.

require 'rubygems'
require 'net/ssh'
require 'etc'

server = 'localhost'

def ssh_exec!(ssh, command)
  stdout_data = ""
  stderr_data = ""
  exit_code = nil
  exit_signal = nil
  ssh.open_channel do |channel|
    channel.exec(command) do |ch, success|
      unless success
        abort "FAILED: couldn't execute command (ssh.channel.exec)"
      end
      channel.on_data do |ch,data|
        stdout_data+=data
      end

      channel.on_extended_data do |ch,type,data|
        stderr_data+=data
      end

      channel.on_request("exit-status") do |ch,data|
        exit_code = data.read_long
      end

      channel.on_request("exit-signal") do |ch, data|
        exit_signal = data.read_long
      end
    end
  end
  ssh.loop
  [stdout_data, stderr_data, exit_code, exit_signal]
end

Net::SSH.start(server, Etc.getlogin) do |ssh|
  puts ssh_exec!(ssh, "true").inspect
  # => ["", "", 0, nil]

  puts ssh_exec!(ssh, "false").inspect  
  # => ["", "", 1, nil]

end

希望这会有所帮助.

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