add berkeley-mono package

common/berkeley-mono.nix

@@ -0,0 +1,24 @@
+# make a  derivation for berkeley-mono font installation
+{ pkgs }:
+
+pkgs.stdenv.mkDerivation {
+  pname = "berkeley-mono";
+  version = "1.009";
+
+  src = ../nix-secrets/resources/berkeley-mono/berkeley-mono-patched.zip;
+
+  unpackPhase = ''
+    runHook preUnpack
+    ${pkgs.unzip}/bin/unzip $src
+
+    runHook postUnpack
+  '';
+
+  installPhase = ''
+    runHook preInstall
+
+    install -Dm644 berkeley-mono-patched/*.ttf -t $out/share/fonts/truetype
+
+    runHook postInstall
+  '';
+}