2 files changed, 29 insertions, 0 deletions
diff --git a/krebs/4lib/default.nix b/krebs/4lib/default.nix
index b67585335..ca7219c7e 100644
--- a/krebs/4lib/default.nix
+++ b/krebs/4lib/default.nix
@@ -14,5 +14,12 @@ builtins // lib // rec {
 
   dns = import ./dns.nix { inherit lib; };
   listset = import ./listset.nix { inherit lib; };
+  shell = import ./shell.nix { inherit lib; };
   tree = import ./tree.nix { inherit lib; };
+
+  toC = x: {
+    list = "{ ${concatStringsSep ", " (map toC x)} }";
+    null = "NULL";
+    string = toJSON x; # close enough
+  }.${typeOf x};
 }
diff --git a/krebs/4lib/shell.nix b/krebs/4lib/shell.nix
new file mode 100644
index 000000000..2a6da5c16
--- /dev/null
+++ b/krebs/4lib/shell.nix
@@ -0,0 +1,22 @@
+{ lib, ... }:
+
+with builtins;
+with lib;
+
+rec {
+  escape =
+    let
+      isSafeChar = c: match "[-./0-9_a-zA-Z]" c != null;
+    in
+    stringAsChars (c:
+      if isSafeChar c then c
+      else if c == "\n" then "'\n'"
+      else "\\${c}");
+
+  #
+  # shell script generators
+  #
+
+  # example: "${cat (toJSON { foo = "bar"; })} | jq -r .foo"
+  cat = s: "printf '%s' ${escape s}";
+}