diff --git a/flake.nix b/flake.nix
index 29c8f3d..66249c1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -96,6 +96,6 @@
         python = import ./hosts/common/shells/python { inherit pkgs; };
       };
 
-      formatter = pkgs.nixfmt-rfc-style;
+      formatter."x86_64-linux" = pkgs.nixfmt-rfc-style;
     };
 }
diff --git a/hosts/common/configs/system/backup/backup.completion.zsh b/hosts/common/configs/system/backup/backup.completion.zsh
new file mode 100644
index 0000000..4600624
--- /dev/null
+++ b/hosts/common/configs/system/backup/backup.completion.zsh
@@ -0,0 +1,16 @@
+_backup_completion() {
+  local options=(
+    '-m[specify partition to mount for backup]:partition:($(_partitions))'
+    '-b[specify backup directory]:backup directory:_files -/'
+  )
+  local curcontext="$curcontext" state line
+  typeset -A opt_args
+
+  _partitions() {
+    lsblk -rno NAME | sed 's/^/\/dev\//'
+  }
+
+  _arguments -s $options
+}
+
+compdef _backup_completion backup
diff --git a/hosts/common/configs/system/backup/backup.sh b/hosts/common/configs/system/backup/backup.sh
new file mode 100644
index 0000000..77d75e5
--- /dev/null
+++ b/hosts/common/configs/system/backup/backup.sh
@@ -0,0 +1,64 @@
+if [[ "${EUID}" -ne 0 ]]; then
+  echo "Please run the script as root."
+  exit 1
+fi
+
+usage() {
+  echo "Usage: $0 [-m partition] [-b backup_location]"
+  exit 1
+}
+
+cleanup() {
+  if [ -d "/persist.bak" ]; then btrfs -q subvolume delete "/persist.bak"; fi
+  if [ -n "${backup_location}" ] && [ -f "${backup_location}.tmp" ]; then rm "${backup_location}.tmp"; fi
+
+  if [ -n "${mount_location}" ]; then
+    if mount | grep -q "${mount_location}"; then umount "${mount_location}"; fi
+    if [ -d "${mount_location}" ]; then rmdir "${mount_location}"; fi
+  fi
+}
+
+partition=""
+backup_location=""
+mount_location=""
+
+trap cleanup EXIT
+
+while getopts "m:b:" opt; do
+  case "${opt}" in
+    m) partition="${OPTARG}" ;;
+    b) backup_location="${OPTARG}" ;;
+    *) usage ;;
+  esac
+done
+
+if [ -n "${partition}" ]; then
+  mount_location=$(mktemp -d /mnt/backup.XXXXXX)
+  echo "Mounting ${partition} at ${mount_location}..."
+  mount "${partition}" "${mount_location}"
+fi
+
+if [ -z "${mount_location}" ]; then
+  if [[ "${backup_location}" != /* ]]; then
+    backup_location="$(realpath "${backup_location}")"
+  fi
+else
+  if [[ "${backup_location}" = /* ]]; then
+    echo "Error: When a partition is mounted, backup_location must be relative."
+    exit 1
+  fi
+
+  backup_location="$(realpath "${mount_location}/${backup_location}")"
+fi
+
+backup_location="${backup_location}/$(hostname)-$(date +%Y-%m-%d-%H-%M-%S).btrfs.gz"
+
+echo "Creating /persist snapshot..."
+btrfs -q subvolume snapshot -r "/persist" "/persist.bak"
+
+echo "Creating backup at ${backup_location}..."
+btrfs -q send "/persist.bak" | gzip > "${backup_location}.tmp"
+
+mv "${backup_location}.tmp" "${backup_location}"
+
+echo "Backup completed successfully!"
diff --git a/hosts/common/configs/system/backup/default.nix b/hosts/common/configs/system/backup/default.nix
new file mode 100644
index 0000000..9c0e152
--- /dev/null
+++ b/hosts/common/configs/system/backup/default.nix
@@ -0,0 +1,20 @@
+{ pkgs, ... }:
+{
+  environment.systemPackages = [
+    (pkgs.writeShellApplication {
+      name = "backup";
+      runtimeInputs = with pkgs; [
+        btrfs-progs
+        coreutils-full
+        util-linux
+      ];
+      text = builtins.readFile ./backup.sh;
+    })
+  ];
+
+  home-manager.sharedModules = [
+    {
+      programs.zsh.initExtra = builtins.readFile ./backup.completion.zsh;
+    }
+  ];
+}
diff --git a/hosts/common/configs/user/console/kubernetes/default.nix b/hosts/common/configs/user/console/kubernetes/default.nix
index 636d68c..7e18072 100644
--- a/hosts/common/configs/user/console/kubernetes/default.nix
+++ b/hosts/common/configs/user/console/kubernetes/default.nix
@@ -27,13 +27,13 @@
           fi
         }
 
-        _kubeswitch-completion() {
+        _kubeswitch_completion() {
           local dir="$HOME/.kube"
           local config="$dir/config"
           compadd -- ''${(f)"$(find "$dir" -maxdepth 1 \( -type f -o -type l \) -not -name 'config' -exec basename {} \;)"}
         }
 
-        compdef _kubeswitch-completion kubeswitch
+        compdef _kubeswitch_completion kubeswitch
       '';
 
       p10k.extraRightPromptElements = [ "kubecontext" ];
diff --git a/hosts/common/configs/user/console/nix-develop/default.nix b/hosts/common/configs/user/console/nix-develop/default.nix
index f6bb465..7c06794 100644
--- a/hosts/common/configs/user/console/nix-develop/default.nix
+++ b/hosts/common/configs/user/console/nix-develop/default.nix
@@ -7,23 +7,27 @@
   home-manager.users.${user}.programs.zsh = {
     shellAliases.nd = "nix-develop";
 
-    initExtra = let
-      devShells = lib.strings.concatStringsSep " " (lib.attrsets.mapAttrsToList (key: _: key) inputs.self.devShells);
-    in ''
-      nix-develop() {
-        if [ -z "$1" ]; then
-          echo "Usage: nix-develop <shell>"
-          return 1
-        fi
-        nix develop self#"$1" -c "$SHELL"
-      }
+    initExtra =
+      let
+        devShells = lib.strings.concatStringsSep " " (
+          lib.attrsets.mapAttrsToList (key: _: key) inputs.self.devShells
+        );
+      in
+      ''
+        nix-develop() {
+          if [ -z "$1" ]; then
+            echo "Usage: nix-develop <shell>"
+            return 1
+          fi
+          nix develop self#"$1" -c "$SHELL"
+        }
 
-      _nix-develop-completion() {
-        local shells=(${devShells})
-        compadd -- $shells
-      }
+        _nix-develop_completion() {
+          local shells=(${devShells})
+          compadd -- $shells
+        }
 
-      compdef _nix-develop-completion nix-develop
-    '';
+        compdef _nix-develop_completion nix-develop
+      '';
   };
 }
diff --git a/hosts/common/configs/user/console/nix-direnv/default.nix b/hosts/common/configs/user/console/nix-direnv/default.nix
index 8202947..050990a 100644
--- a/hosts/common/configs/user/console/nix-direnv/default.nix
+++ b/hosts/common/configs/user/console/nix-direnv/default.nix
@@ -16,34 +16,38 @@
       zsh = {
         shellAliases.nde = "nix-direnv";
 
-        initExtra = let
-          devShells = lib.strings.concatStringsSep " " (lib.attrsets.mapAttrsToList (key: _: key) inputs.self.devShells);
-        in ''
-          nix-direnv() {
-            if [ -z "$1" ]; then
-              echo "use flake" > .envrc
-            else
-              echo "use flake self#$1" > .envrc
-            fi
-
-            if git rev-parse --is-inside-work-tree &> /dev/null && ! grep -q "^\.envrc$" .gitignore .git/info/exclude; then
-              echo "Do you want to hide the .envrc file from git? (y/N)"
-              read -r answer
-              if [[ "$answer" =~ ^[Yy]$ ]]; then
-                echo ".envrc" >> .git/info/exclude
+        initExtra =
+          let
+            devShells = lib.strings.concatStringsSep " " (
+              lib.attrsets.mapAttrsToList (key: _: key) inputs.self.devShells
+            );
+          in
+          ''
+            nix-direnv() {
+              if [ -z "$1" ]; then
+                echo "use flake" > .envrc
+              else
+                echo "use flake self#$1" > .envrc
               fi
-            fi
 
-            direnv allow
-          }
+              if git rev-parse --is-inside-work-tree &> /dev/null && ! grep -q "^\.envrc$" .gitignore .git/info/exclude; then
+                echo "Do you want to hide the .envrc file from git? (y/N)"
+                read -r answer
+                if [[ "$answer" =~ ^[Yy]$ ]]; then
+                  echo ".envrc" >> .git/info/exclude
+                fi
+              fi
 
-          _nix-direnv-completion() {
-            local shells=(${devShells})
-            compadd -- $shells
-          }
+              direnv allow
+            }
 
-          compdef _nix-direnv-completion nix-direnv
-        '';
+            _nix-direnv_completion() {
+              local shells=(${devShells})
+              compadd -- $shells
+            }
+
+            compdef _nix-direnv_completion nix-direnv
+          '';
 
         p10k.extraRightPromptElements = [ "direnv" ];
       };
diff --git a/hosts/common/configs/user/gui/theme/options.nix b/hosts/common/configs/user/gui/theme/options.nix
index 1cc2443..73ed5be 100644
--- a/hosts/common/configs/user/gui/theme/options.nix
+++ b/hosts/common/configs/user/gui/theme/options.nix
@@ -533,6 +533,6 @@ in
       }
     );
 
-    programs.zsh.initExtra = builtins.readFile ./theme.completion.sh;
+    programs.zsh.initExtra = builtins.readFile ./theme.completion.zsh;
   };
 }
diff --git a/hosts/common/configs/user/gui/theme/theme.completion.sh b/hosts/common/configs/user/gui/theme/theme.completion.zsh
similarity index 81%
rename from hosts/common/configs/user/gui/theme/theme.completion.sh
rename to hosts/common/configs/user/gui/theme/theme.completion.zsh
index d5faec1..ae2caec 100644
--- a/hosts/common/configs/user/gui/theme/theme.completion.sh
+++ b/hosts/common/configs/user/gui/theme/theme.completion.zsh
@@ -1,4 +1,4 @@
-_theme-completion() {
+_theme_completion() {
   local options=(
     '-m[set mode: light, dark, or toggle]:mode:(light dark toggle)'
     '-w[set wallpaper: specify file path]:file:_files'
@@ -8,4 +8,4 @@ _theme-completion() {
   _arguments -s $options
 }
 
-compdef _theme-completion theme
+compdef _theme_completion theme
diff --git a/hosts/common/configs/user/gui/theme/theme.sh b/hosts/common/configs/user/gui/theme/theme.sh
index d48ba6b..4874380 100644
--- a/hosts/common/configs/user/gui/theme/theme.sh
+++ b/hosts/common/configs/user/gui/theme/theme.sh
@@ -18,8 +18,9 @@ toggle_mode() {
   fi
 }
 
-show_usage() {
+usage() {
   echo "Usage: theme [-m {light|dark|toggle}] [-w <file>]"
+  exit 1
 }
 
 finish() {
@@ -42,8 +43,7 @@ while getopts "m:w:" opt; do
           toggle_mode
           ;;
         *)
-          show_usage
-          exit 1
+          usage
           ;;
       esac
       ;;
@@ -51,8 +51,7 @@ while getopts "m:w:" opt; do
       set_wallpaper "$OPTARG"
       ;;
     *)
-      show_usage
-      exit 1
+      usage
       ;;
   esac
 done
diff --git a/hosts/eirene/default.nix b/hosts/eirene/default.nix
index 2cfa9f3..03f50b7 100644
--- a/hosts/eirene/default.nix
+++ b/hosts/eirene/default.nix
@@ -7,6 +7,7 @@
     (import ./format.nix { device = "/dev/disk/by-id/nvme-SAMSUNG_MZVL22T0HBLB-00BL2_S64RNE0R602762"; })
     ./hardware
 
+    ../common/configs/system/backup
     ../common/configs/system/bluetooth
     ../common/configs/system/boot
     ../common/configs/system/brightnessctl
diff --git a/hosts/elara/default.nix b/hosts/elara/default.nix
index efaa0e2..e899ddb 100644
--- a/hosts/elara/default.nix
+++ b/hosts/elara/default.nix
@@ -11,6 +11,7 @@
     # elara runs on an external drive on eirene
     ../eirene/hardware
 
+    ../common/configs/system/backup
     ../common/configs/system/bluetooth
     ../common/configs/system/boot
     ../common/configs/system/brightnessctl