rubytest.rb

# create new file and write text to it
io = IO.new(IO.sysopen("textfile.txt", "w+"))

io.write("first line\nsecond line\nthird line\n")

# check that write worked
io.rewind

puts io.sysread(4096)

io.rewind

# test String#prepend and IO#getbyte
tempstr = ""

io.each_char {
    b = io.getbyte
    if (b != nil)
        tempstr.prepend([b].pack("C*"))
    end
}

puts tempstr