diff --git a/implement-shell-tools/cat/cat.py b/implement-shell-tools/cat/cat.py
new file mode 100644
index 00000000..58dccaee
--- /dev/null
+++ b/implement-shell-tools/cat/cat.py
@@ -0,0 +1,52 @@
+import argparse
+from enum import Enum
+
+class Numbering(Enum):
+    NONE = 0
+    ALL = 1
+    NONEMPTY = 2
+
+def print_numbered_line(line, line_number, pad=6):
+    print(f"{line_number:{pad}}\t{line}", end='')
+    return line_number + 1
+
+def cat(filepath, numbering, start_line):
+    line_number = start_line
+    try:
+        with open(filepath) as f:
+            for line in f:
+                if numbering == Numbering.NONEMPTY:
+                    if line.strip():
+                        line_number = print_numbered_line(line, line_number)
+                    else:
+                        print(line, end='')
+                elif numbering == Numbering.ALL:
+                    line_number = print_numbered_line(line, line_number)
+                else:
+                    print(line, end='')
+    except FileNotFoundError:
+        print(f"cat: {filepath}: No such file or directory")
+    return line_number
+
+def main():
+    parser = argparse.ArgumentParser(description="Concatenate files and print on the standard output.")
+    parser.add_argument('-n', action='store_true', help='number all output lines')
+    parser.add_argument('-b', action='store_true', help='number non-empty output lines')
+    parser.add_argument('files', nargs='+', help='files to concatenate')
+    args = parser.parse_args()
+
+    if args.n and args.b:
+        parser.error("options -n and -b are mutually exclusive")
+    elif args.n:
+        numbering = Numbering.ALL
+    elif args.b:
+        numbering = Numbering.NONEMPTY
+    else:
+        numbering = Numbering.NONE
+
+    line_number = 1  # start line numbering
+    for file in args.files:
+        line_number = cat(file, numbering=numbering, start_line=line_number)
+
+if __name__ == "__main__":
+    main()
diff --git a/implement-shell-tools/ls/ls.py b/implement-shell-tools/ls/ls.py
new file mode 100644
index 00000000..bd308276
--- /dev/null
+++ b/implement-shell-tools/ls/ls.py
@@ -0,0 +1,31 @@
+import os
+import argparse
+
+def ls(path, one_column, show_hidden):
+    """List files in a directory, optionally in one column or including hidden files."""
+    try:
+        files = os.listdir(path)
+        if not show_hidden:
+            files = [f for f in files if not f.startswith('.')]
+        files.sort()
+        
+        if one_column:
+            print(*files, sep='\n')
+        else:
+            print(*files)
+    except FileNotFoundError:
+        print(f"ls: cannot access '{path}': No such file or directory")
+    except NotADirectoryError:
+        print(f"ls: cannot access '{path}': Not a directory")
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-1', dest='one_column', action='store_true', help='list one file per line')
+    parser.add_argument('-a', action='store_true', help='show hidden files')
+    parser.add_argument('path', nargs='?', default='.', help='directory to list')
+    args = parser.parse_args()
+    
+    ls(args.path, args.one_column, args.a)
+
+if __name__ == "__main__":
+    main()
diff --git a/implement-shell-tools/wc/wc.py b/implement-shell-tools/wc/wc.py
new file mode 100644
index 00000000..23de6599
--- /dev/null
+++ b/implement-shell-tools/wc/wc.py
@@ -0,0 +1,58 @@
+import argparse
+
+def wc(path, count_lines, count_words, count_bytes):
+    """Count lines, words, and bytes for a single file."""
+    try:
+        with open(path, 'r') as f:
+            content = f.read()
+        lines = content.splitlines()
+        words = content.split()
+        bytes_ = len(content.encode('utf-8'))
+
+        # Determine what to show
+        if not any([count_lines, count_words, count_bytes]):
+            count_lines = count_words = count_bytes = True
+
+        parts = []
+        if count_lines: parts.append(str(len(lines)))
+        if count_words: parts.append(str(len(words)))
+        if count_bytes: parts.append(str(bytes_))
+
+        print(' '.join(parts), path)
+
+        return (len(lines) if count_lines else 0,
+                len(words) if count_words else 0,
+                bytes_ if count_bytes else 0)
+    except FileNotFoundError:
+        print(f"wc: {path}: No such file or directory")
+        return (0, 0, 0)
+    except IsADirectoryError:
+        print(f"wc: {path}: Is a directory")
+        return (0, 0, 0)
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-l', action='store_true', help='Count lines')
+    parser.add_argument('-w', action='store_true', help='Count words')
+    parser.add_argument('-c', action='store_true', help='Count bytes')
+    parser.add_argument('paths', nargs='+', help='Files to count')
+    args = parser.parse_args()
+
+    total_lines = total_words = total_bytes = 0
+    multiple_files = len(args.paths) > 1
+
+    for path in args.paths:
+        l, w, b = wc(path, args.l, args.w, args.c)
+        total_lines += l
+        total_words += w
+        total_bytes += b
+
+    if multiple_files:
+        parts = []
+        if args.l or not any([args.l, args.w, args.c]): parts.append(str(total_lines))
+        if args.w or not any([args.l, args.w, args.c]): parts.append(str(total_words))
+        if args.c or not any([args.l, args.w, args.c]): parts.append(str(total_bytes))
+        print(' '.join(parts), 'total')
+
+if __name__ == "__main__":
+    main()