Lua, Lilypond, and Linux

[David Bellows]

OK, I know this might be way too specific a question for this list but
I'm hoping.

Here is example.ly

\version "2.19.17"
{
  c' e' g' e'
}

And lily.lua for Lua 5.3

os.execute("lilypond example.ly &> lily.txt")

And then from the command line:

lua lily.lua

I'm trying to suppress any of Lilypond's output from going to the
screen but into some other file. From the command line running just:

lilypond example.ly &> lily.txt

works as expected but for some reason when running that command in Lua
nothing gets written to lily.txt and everything goes to the screen.

I'm not sure if this is a problem with Lua or Bash or Linux or me, but
any help would be appreciated. For what it's worth having the line in
my Lua file:

os.execute("pdflatex example.tex > latex.txt")

works exactly as expected(!).

Thanks,
Dave