Printing a file to a printer in Ruby

Question

I need help with sending a formatted text to a printer using Ruby on Ruby on Rails OR sending a pdf file to a printer from Ruby program. I can write the code to create a pdf

Answer 1

I have an internal app for creating computer labels. I import computers from a file I get from Dell or enter them manually, I export them to a CSV that I can import into MS SCCM. I can print labels to put on computers. The labels have a company logo, the computer name, MAC address and servicedesk contact info.

I print it with gLabels. You design a label in gLabels, enter dynamic fields and feed a CSV to it and it spits out a PDF which I then use lpr to print to my Dymo Labelwriter.

I put it in my Computers model because I didn't know where else to put it.

# Print all computers with printed = false
def self.print
  printed_labels = 0 
  csv_file = Tempfile.new(["computers", ".csv"])
  logger.debug("Writing #{csv_file.path}")
  begin
    Computer.transaction do
      Computer.unprinted.each do |computer|
        csv_file.puts "\"#{computer.mac(' ')}\",\"#{computer.hostname}\""
        computer.printed = true
        computer.save
        printed_labels += 1
      end
    end 
  ensure
    csv_file.close
    if csv_file.length > 0 
      pdf_file = Tempfile.new(["computers", ".pdf"])
      begin
        pdf_file.close
        system '/usr/bin/glabels-batch', "--input=#{csv_file.path}", "--output=#{pdf_file.path}", AssetBase::Application.config.computer_label
        system '/usr/bin/lpr', '-P', 'LabelWriter-450', pdf_file.path
      ensure
        pdf_file.unlink
      end
    end
    csv_file.unlink
  end   
  printed_labels
end

This runs on Fedora Linux so the printer backend is CUPS and what part of it that handles PDF I don't know. It could be CUPS or the printer driver or the printer driver itself.

There are other methods of creating structured text to PDF but for labels gLabels is great.