add hosts/modules/bashistrans.nix

hosts/modules/bashistrans.nix

@@ -0,0 +1,23 @@
+{pkgs, ...}: {
+  # I want to use fish as my login shell but it always goes terrible
+  # cause it isn't POSIX compliant, so instead Bash is my login and
+  # will just exec fish (^-^)
+  programs.bash = {
+    blesh.enable = false; # ble.sh replacement for GNU readline
+    completion.enable = true;
+
+    interactiveShellInit = ''
+      # help bash transition into a beautiful fish!
+      if [[ -z $CRY_BASH_IS_TRANS ]]
+      then
+        if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
+        then
+          shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
+          exec ${pkgs.fish}/bin/fish $LOGIN_OPTION
+        fi
+      fi
+      # bash is trans now! (no more transitioning required)
+      export CRY_BASH_IS_TRANS=true
+    '';
+  };
+}