> > > cat a
> > one\
> > two
> > irb(main):001:0> a=File.read("a")
> > => "one\\\ntwo\n"
> > irb(main):002:0> b=File.readlines("a")
> > => ["one\\\n", "two\n"]
> > 
> > I would like instead:
> >  
> >  f=File.readlines("a")
> >  ["onetwo\n"]

Alternative solution: how about joining the adjacent strings together
in-place after reading them in?

lastline = ""
a.delete_if do |line|
  if lastline.gsub!(/\\\n\z/,line)
    true
  else
    lastline = line
    false
  end
end

which can be even further obfuscated to:

lastline = ""
a.delete_if do |line|
  lastline.gsub!(/\\\n\z/,line) or not lastline = line
end

# before: a=["one\n", "two\\\n", "three\\\n", "four\n", "five\n"]
# after:  a=["one\n", "twothreefour\n", "five\n"]

Regards,

Brian.