let glob ?(null=false) (args:filexpr) =
let shopt = ("shopt "^(if null then "-s" else "-u")^" nullglob\n") in
let cmd = shopt^"for i in \"$@\"; do echo $i; done" in
make ~at:Treat.identity ~ot:String.Text.of_string cmd ~script:true ~args:(Some args) ()