CODEWITHSUNDEEP
rubytelnet
Stewart Johnson
Stewart Johnson

Reputation: 14449

how to read whole lines using ruby's net/telnet?

I'm using the net/telnet library in ruby to read data from a server. It's sending commands as whole lines with a newline at the end, so I thought I'd do this:

connection = Net::Telnet.new(options)

connection.waitfor(/\n/) do |txt|
  process txt
end

That doesn't work because it sends me a whole bunch of lines all at once. I can fix that fairly easily by instead doing:

connection.waitfor(/\n/) do |txt|
  txt.split("\n").each do |line|
    process line
  end
end

Except there's a problem with that too: the string I'm sent almost always contains half a command at the end. i.e.: if the server was sending this:

COMMAND1 option1 option2 option3
COMMAND2 option1 option2 option3
COMMAND3 option1 option2 option3

I'll often get this:

COMMAND1 option1 option2 option3
COMMAND2 option1 option2 option3
COMMAND3 opt

and then I'll get the rest of COMMAND3's options in the next read, along with COMMAND4.

Is there any way I can get net/telnet to just send me text delimited on the newlines? Or another way to fix this?

Thanks, Stewart

Upvotes: 2

Views: 1577

Answers (1)

Stewart Johnson
Stewart Johnson

Reputation: 14449

So this is my current solution, I'm not sure if it's the best way to go but it works okay on my live data source:

connection = Net::Telnet.new(options)

all_text = ""
while running do
  connection.waitfor(/\n/) do |server_text|
    all_text += server_text
    while cmd = all_text.slice!(/^.*\n/) do
      process cmd
    end
    # any half-command remains in all_text at this point
  end
end

Upvotes: 1

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