(with-input-from-file "/dev/null"
  (lambda ()
    (with-output-to-file "/dev/null"
      (lambda ()
        (with-error-to-file "/dev/null"
          (lambda ()
            (if (= 0 (primitive-fork))
                (execl "/run/current-system/profile/bin/echo" "echo" "you can not see me!\n"))))))))

#> guile asdf.scm
#> you can not see me!