* Utility: the generic substituter. It substitutes all occurences of

`@var@' in the file `src', writing the result to $out, where `var'
  is any environment variable starting with a lowercase character.
  Example:

    genericSubstituter {
      src = ./file;
      foo = "bla";
      shell = bash + "/bin/sh";
    };

  will replace `@foo@' with `bla' and `@shell@' with
  `/nix/store/...-bash-.../bin/sh'.

svn path=/nixpkgs/trunk/; revision=6928

pkgs/build-support/substitute/generic-substituter.nix

@@ -0,0 +1,10 @@
+{stdenv}:
+
+args:
+
+stdenv.mkDerivation ({
+  name = if args ? name then args.name else baseNameOf (toString args.src);
+  builder = ./generic-substituter.sh;
+  substitute = ./substitute.sh;
+  inherit (args) src;
+} // args)

pkgs/build-support/substitute/generic-substituter.sh

@@ -0,0 +1,16 @@
+source $stdenv/setup
+source $substitute
+
+args=
+
+# Select all environment variables that start with a lowercase character.
+for envVar in $(env | sed "s/^[^a-z].*//" | sed "s/^\([^=]*\)=.*/\1/"); do
+    echo "$envVar -> ${!envVar}"
+    args="$args --subst-var $envVar"
+done
+
+substitute $src $out $args
+
+if test -n "$isExecutable"; then
+    chmod +x $out
+fi

pkgs/top-level/all-packages.nix

@@ -188,6 +188,10 @@ rec {
 
   substituter = ../build-support/substitute/substitute.sh;
 
+  genericSubstituter = import ../build-support/substitute/generic-substituter.nix {
+    inherit stdenv;
+  };
+
 
   ### TOOLS