Using Net::SSH in an `initialize` block does not work

Question

I want to connect to a remote server and run some commands there. For that I am writing the following Ruby script and it works fine.

@hostname = "SERVER_NAME"
@username = "user"
@password = "pass"
@cmd = "ls -alt"

begin
  @ssh = Net::SSH.start(@hostname, @username, :password => @password)
  puts "#{@ssh}"
  res = @ssh.exec!(@cmd)
  @ssh.close
  puts res
rescue
  puts "Unable to connect to #{@hostname} using #{@username}/#{@password}"
end

But when I try to put the same code in an initialize block it is not working. Below is the code for that:

def initialize(hostname, user, password)
  @hostname = "#{hostname}"
  @username = "#{user}"
  @password = "#{password}"

  begin
    puts "entered begin"
    @ssh = Net::SSH.start(@hostname, @username, :password => @password)
    puts "#{@ssh}"
    res = @ssh.exec!(@cmd)
    puts "#{res}"
    # @ssh.close
    puts res
  rescue => e
    puts e
    puts "#{@ssh} Unable to connect to #{@hostname} using #{@username}/#{@password}"
  end
end

Printing @ssh gives different results in first and second chunk of code.

Can some one help me in figuring out what's going wrong?

As an aside, "#{hostname}" shouldn't be there. Either use hostname.to_s to convert to a string, or drop the string conversion entirely, because hostname should be a string already. Same for user and password. — user229044
– user229044 ♦, Commented Nov 12, 2014 at 14:42
Thank you for the quick replies. Setting up @cmd in initialize block fixed the problem. — itsh
– itsh, Commented Nov 12, 2014 at 14:52
Please link to the answer. There is no submitted answer for this question. Right now, it is not viewed as "answered" because there are no submitted answers through it. (Comments do not count as answers.) Please Enter your answer, with an explanation, in "Your Answer" and click "Post your answer" — user3373470
– user3373470, Commented Aug 14, 2015 at 15:33

Community · Accepted Answer · 2017-05-23 12:14:33Z

1

Problem was that I did not initialize @cmd in initialize block. That is why it was not working as expected. I fixed it as recommended by @ptierno. Below is the working code:

def initialize(hostname, user, password)
  @hostname = "#{hostname}"
  @username = "#{user}"
  @password = "#{password}"
  @cmd = "ls -alt"

  begin
    puts "entered begin"
    @ssh = Net::SSH.start(@hostname, @username, :password => @password)
    puts "#{@ssh}"
    res = @ssh.exec!(@cmd)
    puts "#{res}"
    # @ssh.close
    puts res
  rescue => e
    puts e
    puts "#{@ssh} Unable to connect to #{@hostname} using #{@username}/#{@password}"
  end
end

edited May 23, 2017 at 12:14

CommunityBot

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answered Aug 14, 2015 at 15:39

itsh

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