switch to s6-linux-init and s6-rc

This is at the point where it runs a getty and a pile of s6-supervise
processes, though it doesn't seem to run the things being supervised

pkgs/pseudofile/default.nix

@@ -0,0 +1,37 @@
+{
+  writeText
+, lib
+}:
+filename  : attrset :
+let
+  inherit (lib.debug) traceSeqN;
+  inherit (lib.attrsets) mapAttrsToList;
+  visit = prefix: attrset:
+    let
+      qprint = msg : builtins.replaceStrings ["\n" "=" "\""] ["=0A" "=3D" "=22"] msg;
+      l =
+        mapAttrsToList
+          (filename: attrs:
+            let
+              attrs' = {type = "f"; } // attrs;
+              mode = if attrs ? mode then attrs.mode else
+                (if attrs'.type == "d" then "0755" else "0644");
+              line = "${prefix}/${filename} ${attrs'.type} ${mode} 0 0";
+            in
+              if attrs'.type == "f" then
+                "${line} echo -n \"${qprint attrs'.file}\" |qprint -d"
+              else if attrs'.type == "d" then
+                (visit "${prefix}/${filename}" attrs.contents) +
+                "\n" + line
+              else if attrs'.type == "s" then
+                "${line} ${attrs'.target}"
+              else if attrs'.type == "l" then
+                "${prefix}/${filename} l ${attrs'.target}"
+              else if attrs'.type == "i" then
+                "${line} ${attrs.subtype}"
+              else
+                line)
+          attrset;
+    in builtins.concatStringsSep "\n" l;
+  res =  (visit "" attrset);
+in writeText filename res