diff --git a/flake.nix b/flake.nix
index 570b81c..d078651 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,6 +8,38 @@
 
   outputs = { self, nixpkgs, flake-utils }: flake-utils.lib.eachDefaultSystem (system:
     with nixpkgs.legacyPackages.${system}; {
+      devShells = {
+        elegant =
+          (pkgs.buildFHSUserEnv {
+            name = "elegant-builder";
+            targetPkgs = pkgs:
+              (with pkgs; [
+                gcc
+                bintools
+                zlib.dev
+                readline
+                gsl
+                lesstif
+                openblas.dev
+                gfortran
+                # (stdenv.lib.getLib gfortran.cc)
+              ]) ++ (with pkgs.xorg;
+              [
+                libX11.dev
+                xorgproto
+                libXt.dev
+                libSM.dev
+                libICE.dev
+                libXmu.dev
+              ]);
+            runScript = "bash";
+            profile = ''
+              export HOST_ARCH="linux-x86_64"
+              export EPICS_HOST_ARCH="linux-x86_64"
+              export NIX_LDFLAGS="$NIX_LDFLAGS -L${gfortran.cc.lib}/lib"
+            '';
+          }).env // { };
+      };
       packages = {
         tracy = stdenv.mkDerivation rec {
           pname = "tracy";
@@ -41,12 +73,62 @@
             url = https://ops.aps.anl.gov/downloads/defns.rpn;
             sha256 = "62fadae99cef2c18d51be8a68c3012099a773c3a757323e5b7565344cd3ae358";
           };
-          base = mkDerivation {
-            src = fetchurl
-              {
+          elegant = stdenv.mkDerivation {
+            name = "elegant";
+            buildInputs = [ gcc perl ];
+            # nativeBuildInputs = [ breakpointHook ];
+            sourceRoot = ".";
+            HOST_ARCH = "linux-x86_64";
+            EPICS_HOST_ARCH = "linux-x86_64";
+            srcs = [
+              (fetchurl {
                 url = https://ops.aps.anl.gov/downloads/epics.base.configure.tar.gz;
-                sha256 = "62fadae99cef2c18d51be8a68c3012099a773c3a757323e5b7565344cd3ae358";
-              };
+                sha256 = "wn5DJRoqcUZMbrZY9xOf0/ECLVKxTKjgVTztIkVq0eM=";
+              })
+              (fetchurl {
+                url = https://ops.aps.anl.gov/downloads/epics.extensions.configure.tar.gz;
+                sha256 = "RtuDv34MxwvmY6gi5MsinLA/UumOaSD7wc4YHfnqxZs=";
+              })
+              (fetchurl {
+                url = https://ops.aps.anl.gov/downloads/SDDS.5.1.tar.gz;
+                sha256 = "VOUjrQpjrZiu4ez8jnJL7ShOZLKqLpm4d2dqAQORc+I=";
+              })
+              (fetchurl {
+                url = https://ops.aps.anl.gov/downloads/oag.apps.config.tar.gz;
+                sha256 = "6RyWEYUr5xKv7rcbPQO8nhVy1zCPJa+qheSMvodUbPE=";
+              })
+              (fetchurl {
+                url = https://ops.aps.anl.gov/downloads/oag.apps.configure.tar.gz;
+                sha256 = "IjdRThRysntZk56KaBNTYX4KZN3KpHfSS7igvk9Qx1g=";
+              })
+              (fetchurl {
+                url = https://ops.aps.anl.gov/downloads/elegant.2021.4.0.tar.gz;
+                sha256 = "7Ruobl3TL6FUqIemoGBw1Oc+eSeKCMEtsIMyuhx2EMs=";
+              })
+            ];
+            # fix /usr/gcc error
+            # prePatch = ''
+            #   substituteInPlace Makefile \
+            #   --replace '/usr/bin/xcrun clang' clang
+            # '';
+            unpackPhase = ''
+              mkdir src && cd src
+              for src in $srcs; do tar xf $src; done
+            '';
+            # configurePhase = ''
+            buildPhase = ''
+              base=`pwd`
+              cd $base/epics/base
+              make
+              cd $base/epics/extensions/configure
+              make
+              cd $base/epics/extensions/src/SDDS
+              make
+              cd $base/oag/apps/configure
+              make
+              cd $base/oag/apps/src/physics 
+              make
+            '';
           };
         };
       };