This should theoretically eject most cash drawers, but needs testing with actual hardware

eject.rb

@printer = "/dev/lp0"
File.open(@printer, "w") do |f|
  f.print("#{27.chr}#{112.chr}#{0.chr}#{50.chr}#{250.chr}") # Citizen or Bixolon or IBM or Ithaca or Nexa or Olivetti or Pos-X or Posiflex or Samsung
  f.print("#{7.chr}") # Citizen or IBM or Start or Westrex
  f.print("#{27.chr}#{112.chr}#{48.chr}#{55.chr}#{121.chr}") # Bixolon or Epson or Samsung
  f.print("#{27.chr}#{112.chr}#{0.chr}#{100.chr}#{250.chr}") # TEC or Toshiba or Unisys
  f.print("#{27.chr}#{112.chr}#{0.chr}#{48.chr}#{251.chr}") # Axiohm or Fujitsu
  f.print("#{27.chr}#{112.chr}#{0.chr}#{25.chr}#{250.chr}") # Epson or Samsung
  f.print("#{27.chr}#{112.chr}#{0.chr}#{64.chr}#{240.chr}") # Epson or Samsung
  f.print("#{27.chr}#{112.chr}#{1.chr}#{50.chr}#{250.chr}") # Citizen (Drawer 2)
  f.print("#{7.chr}#{27.chr}") # Citizen
  f.print("#{27.chr}#{112}#{1.chr}#{49.chr}#{251.chr}") # Axiohm
  f.print("#{27.chr}#{112.chr}#{32.chr}#{25.chr}") # Epson
  f.print("#{27.chr}#{70.chr}#{0.chr}#{50.chr}#{50.chr}") # Epson
  f.print("#{27.chr}#{112.chr}") # Epson
  f.print("#{27.chr}#{112.chr}#{0.chr}#{50.chr}#{250.chr}") # Epson
  f.print("#{27.chr}#{113.chr}#{0.chr}#{25.chr}#{250.chr}") # Epson
  f.print("#{27.chr}#{25.chr}#{247.chr}") # Epson
  f.print("#{27.chr}#{120.chr}#{1.chr}") # Ithaca
  f.print("#{27.chr}#{112.chr}#{0.chr}#{55.chr}") # NCR
  f.print("#{27.chr}#{112.chr}#{1.chr}#{55.chr}") # NCR (drawer 2)
  f.print("#{27.chr}#{112.chr}#{80.chr}#{25.chr}#{250.chr}") # Posiflex
  f.print("#{27.chr}#{112.chr}#{0.chr}#{48.chr}#{50.chr}") # Samsung
  f.print("#{27.chr}#{112.chr}#{0.chr}#{60.chr}#{240.chr}") # Samsung
  f.print("#{27.chr}#{7.chr}#{11.chr}#{55.chr}#{7.chr}") # Star
  f.print("#{27.chr}#{122.chr}#{49.chr}#{7.chr}") # Star
  f.print("#{27.chr}#{7.chr}#{10.chr}#{50.chr}#{7.chr}") # Star
  f.print("#{27.chr}#{112.chr}#{32.chr}#{55.chr}#{255.chr}") # Toshiba
  f.print("#{27.chr}#{112.chr}#{1.chr}#{49.chr}#{251.chr}") # TPG
  f.print("#{27.chr}#{112.chr}#{0.chr}#{8.chr}#{8.chr}") # TPG
  f.print("#{27.chr}#{112.chr}#{49.chr}#{48.chr}#{48.chr}") # Wasp
end