Change the way NixOS handles environment variables, NixOSize environment configuration, make it possible not to use Bash, add support for Zsh.

modules/config/fonts/fontconfig.nix

@@ -46,13 +46,10 @@ with pkgs.lib;
         </fontconfig>
       '';
 
-    environment.shellInit =
-      ''
-        # FIXME: This variable is no longer needed, but we'll keep it
-        # around for a while for applications linked against old
-        # fontconfig builds.
-        export FONTCONFIG_FILE=/etc/fonts/fonts.conf
-      '';
+    # FIXME: This variable is no longer needed, but we'll keep it
+    # around for a while for applications linked against old
+    # fontconfig builds.
+    environment.variables.FONTCONFIG_FILE.value = "/etc/fonts/fonts.conf";
 
     environment.systemPackages = [ pkgs.fontconfig ];
 

modules/config/i18n.nix

@@ -69,10 +69,7 @@ in
 
     environment.systemPackages = [ glibcLocales ];
 
-    environment.shellInit =
-      ''
-        export LANG=${config.i18n.defaultLocale}
-      '';
+    environment.variables.LANG.value = config.i18n.defaultLocale;
 
     # ‘/etc/locale.conf’ is used by systemd.
     environment.etc = singleton

modules/config/shells-environment.nix

@@ -0,0 +1,202 @@
+# This module defines a global environment configuration and
+# a common configuration for all shells.
+
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let
+
+  cfg = config.environment;
+
+  environOpts = { name, config, ... }: {
+
+    options = {
+
+      value = mkOption {
+        example = "/foo/bin";
+        description =
+          ''
+            Variable value.
+            Exactly one of this or <option>list</option> must be set.
+          '';
+        type = types.uniq types.string;
+      };
+
+      list = mkOption {
+        default = null;
+        example = [ "/foo/bin" "/bar/bin" ];
+        description =
+          ''
+            Variable value.
+            Exactly one of this or <option>value</option> must be set.
+          '';
+        type = types.nullOr (types.listOf types.string);
+      };
+
+    };
+
+    config = {
+      value = mkIf (config.list != null)
+        (concatStringsSep ":" config.list);
+    };
+
+  };
+
+in
+
+{
+
+  options = {
+
+    environment.variables = mkOption {
+      default = {};
+      description = ''
+        A set of environment variables used in the global environment.
+      '';
+      type = types.attrsOf types.optionSet;
+      options = [ environOpts ];
+    };
+
+    environment.profiles = mkOption {
+      default = [];
+      description = ''
+        A list of profiles used to setup the global environment.
+      '';
+      type = types.listOf types.string;
+    };
+
+    environment.profileVariables = mkOption {
+      default = (p: {});
+      description = ''
+        A function which given a profile path should give back
+        a set of environment variables for that profile.
+      '';
+      # !!! this should be of the following type:
+      #type = types.functionTo (types.attrsOf (types.optionSet envVar));
+      # and envVar should be changed to something more like environOpts.
+      # Having unique `value' _or_ multiple `list' is much more useful
+      # than just sticking everything together with ':' unconditionally.
+      # Anyway, to have this type mentioned above
+      # types.optionSet needs to be transformed into a type constructor
+      # (it has a !!! mark on that in nixpkgs)
+      # for now we hack all this to be
+      type = types.functionTo (types.attrsOf (types.listOf types.string));
+    };
+
+    # !!! isn't there a better way?
+    environment.extraInit = mkOption {
+      default = "";
+      description = ''
+        Shell script code called during global environment initialisation
+        after all variables and profileVariables have been set.
+        This code is asumed to be shell-independent, which means you should
+        stick to pure sh without sh word split.
+      '';
+      type = types.lines;
+    };
+
+    environment.shellInit = mkOption {
+      default = "";
+      description = ''
+        Shell script code called during shell initialisation.
+        This code is asumed to be shell-independent, which means you should
+        stick to pure sh without sh word split.
+      '';
+      type = types.lines;
+    };
+
+    environment.loginShellInit = mkOption {
+      default = "";
+      description = ''
+        Shell script code called during login shell initialisation.
+        This code is asumed to be shell-independent, which means you should
+        stick to pure sh without sh word split.
+      '';
+      type = types.lines;
+    };
+
+    environment.interactiveShellInit = mkOption {
+      default = "";
+      description = ''
+        Shell script code called during interactive shell initialisation.
+        This code is asumed to be shell-independent, which means you should
+        stick to pure sh without sh word split.
+      '';
+      type = types.lines;
+    };
+
+    environment.shellAliases = mkOption {
+      default = {};
+      example = { ll = "ls -l"; };
+      description = ''
+        An attribute set that maps aliases (the top level attribute names in
+        this option) to command strings or directly to build outputs. The
+        aliases are added to all users' shells.
+      '';
+      type = types.attrs; # types.attrsOf types.stringOrPath;
+    };
+
+    environment.binsh = mkOption {
+      default = "${config.system.build.binsh}/bin/sh";
+      example = "\${pkgs.dash}/bin/dash";
+      type = with pkgs.lib.types; path;
+      description = ''
+        The shell executable that is linked system-wide to
+        <literal>/bin/sh</literal>. Please note that NixOS assumes all
+        over the place that shell to be Bash, so override the default
+        setting only if you know exactly what you're doing.
+      '';
+    };
+
+    environment.shells = mkOption {
+      default = [];
+      example = [ "/run/current-system/sw/bin/zsh" ];
+      description = ''
+        A list of permissible login shells for user accounts.
+        No need to mention <literal>/bin/sh</literal>
+        here, it is placed into this list implicitly.
+      '';
+      type = types.listOf types.path;
+    };
+
+  };
+
+  config = {
+
+    system.build.binsh = pkgs.bashInteractive;
+
+    environment.etc."shells".text =
+      ''
+        ${concatStringsSep "\n" cfg.shells}
+        /bin/sh
+      '';
+
+    environment.etc."environment".text =
+       ''
+         ${concatStringsSep "\n" (
+           (mapAttrsToList (n: v: ''export ${n}="${concatStringsSep ":" v}"'')
+             # This line is a kind of a hack because of !!! note above
+             (fold (mergeAttrsWithFunc concat) {} ([ (mapAttrs (n: v: [ v.value ]) cfg.variables) ] ++ map cfg.profileVariables cfg.profiles))))}
+
+         ${cfg.extraInit}
+
+         # The setuid wrappers override other bin directories.
+         export PATH="${config.security.wrapperDir}:$PATH"
+
+         # ~/bin if it exists overrides other bin directories.
+         export PATH="$HOME/bin:$PATH"
+       '';
+
+    system.activationScripts.binsh = stringAfter [ "stdio" ]
+      ''
+        # Create the required /bin/sh symlink; otherwise lots of things
+        # (notably the system() function) won't work.
+        mkdir -m 0755 -p /bin
+        ln -sfn "${cfg.binsh}" /bin/.sh.tmp
+        mv /bin/.sh.tmp /bin/sh # atomically replace /bin/sh
+      '';
+
+  };
+
+}

modules/config/timezone.nix

@@ -24,11 +24,8 @@ with pkgs.lib;
 
   config = {
 
-    environment.shellInit =
-      ''
-        export TZDIR=/etc/zoneinfo
-        export TZ=${config.time.timeZone}
-      '';
+    environment.variables.TZDIR.value = "/etc/zoneinfo";
+    environment.variables.TZ.value = config.time.timeZone;
 
     environment.etc.localtime.source = "${pkgs.tzdata}/share/zoneinfo/${config.time.timeZone}";
 

modules/module-list.nix

@@ -13,7 +13,7 @@
   ./config/nsswitch.nix
   ./config/power-management.nix
   ./config/pulseaudio.nix
-  ./config/shells.nix
+  ./config/shells-environment.nix
   ./config/swap.nix
   ./config/sysctl.nix
   ./config/system-path.nix
@@ -45,13 +45,15 @@
   ./programs/bash/bash.nix
   ./programs/bash/command-not-found.nix
   ./programs/blcr.nix
+  ./programs/environment.nix
   ./programs/info.nix
   ./programs/shadow.nix
   ./programs/shell.nix
   ./programs/ssh.nix
   ./programs/ssmtp.nix
   ./programs/venus.nix
   ./programs/wvdial.nix
+  ./programs/zsh/zsh.nix
   ./rename.nix
   ./security/apparmor.nix
   ./security/apparmor-suid.nix

modules/profiles/installation-device.nix

@@ -50,9 +50,7 @@ with pkgs.lib;
     # Tell the Nix evaluator to garbage collect more aggressively.
     # This is desirable in memory-constrained environments that don't
     # (yet) have swap set up.
-    environment.shellInit =
-      ''
-        export GC_INITIAL_HEAP_SIZE=100000
-      '';
+    environment.variables.GC_INITIAL_HEAP_SIZE.value = "100000";
+
   };
 }