diff --git a/sync.py b/sync.py
new file mode 100644
index 0000000..7fd6f44
--- /dev/null
+++ b/sync.py
@@ -0,0 +1,99 @@
+from genericpath import exists
+from typing import Iterable
+from enum import Enum
+from math import nan
+import os
+from os import path
+from pathlib import Path
+
+
+backup_root: str = path.dirname(__file__)
+user_home: str = path.expanduser("~")
+
+if user_home == "~":
+    print("WARN: Cannot read the user home dir, do you run it in the correct script?")
+    print("continue? [y/N]")
+    if (input().lower != 'y'):
+        exit()
+else:
+    print("dot-config: current user home: " + user_home)
+
+def sorted_paths (paths: Iterable[str]) -> list[str]:
+    fin = sorted(paths)
+    return fin
+
+def de_abs_path (path: str) -> str:
+    return path.strip('/').strip('\\')
+
+class BackupItem:
+    def __init__ (self, backup_dir: str, origin_dir: str) -> None:
+        self.name: str = backup_dir
+        self.backup_dir: str = path.join(backup_root, backup_dir)
+        self.origin_dir: str = path.abspath(path.expanduser(origin_dir))
+
+table: list[BackupItem] = [
+    BackupItem("PowerShell", "~/Documents/PowerShell")
+]
+
+def execute_sync (backupItem: BackupItem) -> None:
+    print(f">>> executing backup for {backupItem.name}")
+    all_files_tmp: list[str] = []
+    def walk_dir (walking_dir: str):
+        for root, dirs, files in os.walk(walking_dir):
+            common_root: str = path.commonpath([root, walking_dir])
+            if common_root == walking_dir:
+                relative_root: str = root[len(walking_dir):]
+            else:
+                print(f"WARN: cannot find common root for {root} and {walking_dir}, will break this dir.")
+                continue 
+            for file in files:
+                relative_file_path = de_abs_path(path.join(relative_root, file))
+                # print(f"find file in source: {`relative_file_path`}")
+                all_files_tmp.append(relative_file_path)
+    walk_dir(backupItem.origin_dir)
+    walk_dir(backupItem.backup_dir)
+    all_files: list[str] = sorted_paths(set(all_files_tmp))
+    for file in all_files:
+        compare_file(backupItem, file)
+    # print("\n".join(all_files))
+
+def compare_file (rootBackItem: BackupItem, relative_file_path: str) -> None:
+    class IsNewerStatus (Enum):
+        OLDER = -1
+        NEWER = 1
+        DIFFERENT = nan
+        SAME = 0
+    class FileStatus:
+        def __init__(self, realpath: str) -> None:
+            self.path = realpath
+            self.exists = path.exists(realpath)
+            if self.exists:
+                self.size = path.getsize(realpath)
+                self.edited_time = path.getmtime(realpath)
+        def isNewerThan (self, other):
+            # type: (FileStatus) -> IsNewerStatus
+            if not self.exists:
+                return IsNewerStatus.OLDER
+            if not other.exists:
+                return IsNewerStatus.NEWER
+            if self.edited_time > other.edited_time:
+                return IsNewerStatus.NEWER
+            elif self.edited_time < other.edited_time:
+                return IsNewerStatus.OLDER
+            if self.size != other.size:
+                return IsNewerStatus.DIFFERENT
+            return IsNewerStatus.SAME
+    backup_item: FileStatus = FileStatus(path.join(rootBackItem.backup_dir, relative_file_path))
+    origin_item: FileStatus = FileStatus(path.join(rootBackItem.origin_dir, relative_file_path))
+    match origin_item.isNewerThan(backup_item):
+        case IsNewerStatus.SAME:
+            print(f"{relative_file_path} : is same")
+        case IsNewerStatus.OLDER:
+            print(f"{relative_file_path} : backup file is newer")
+        case IsNewerStatus.NEWER:
+            print(f"{relative_file_path} : original file is newer")
+        case IsNewerStatus.DIFFERENT:
+            print(f"{relative_file_path} : WARN : backup is different but cannot determine which is newer")
+
+for i in table:
+    execute_sync(i)