Completed implementing shell tools in python.

Author: eyuell21

implement-shell-tools/cat/my_cat.py

@@ -0,0 +1,52 @@
+import argparse
+import sys
+
+parser = argparse.ArgumentParser(
+    description="Reads and prints one or more files, optionally numbering lines continuously"
+)
+parser.add_argument("paths", nargs='+', help="One or more file paths")
+parser.add_argument("-n", "--number", action="store_true", help="Number all output lines")
+parser.add_argument("-b", "--number-nonblank", action="store_true", help="Number non-empty output lines")
+
+args = parser.parse_args()
+
+file_paths = args.paths
+number_nonblank = args.number_nonblank
+number_all = args.number and not number_nonblank
+
+line_number = 1
+
+for path in file_paths:
+    try:
+        with open(path, 'r', encoding='utf-8') as f:
+            lines = f.readlines()
+
+        if number_nonblank:
+            nonblank_lines = [line for line in lines if line.strip()]
+            max_digits = len(str(len(nonblank_lines)))
+
+            for line in lines:
+                if line.strip() == "":
+                    print()
+                else:
+                    num_str = str(line_number).rjust(max_digits)
+                    print(f"{num_str}\t{line.rstrip()}")
+                    line_number += 1
+
+        elif number_all:
+            max_digits = len(str(len(lines) * len(file_paths)))
+
+            for line in lines:
+                num_str = str(line_number).rjust(max_digits)
+                print(f"{num_str}\t{line.rstrip()}")
+                line_number += 1
+
+        else:
+            for line in lines:
+                print(line, end='')
+            if not lines[-1].endswith('\n'):
+                print()
+
+    except Exception as e:
+        print(f'Error reading file "{path}": {e}', file=sys.stderr)
+        sys.exit(1)

implement-shell-tools/ls/my_ls.py

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+import os
+import sys
+import stat
+import argparse
+
+parser = argparse.ArgumentParser(
+    description="List files in a directory (simplified ls implementation)"
+)
+parser.add_argument("paths", nargs="*", default=["."], help="One or more file or directory paths")
+parser.add_argument("-l", "--longList", action="store_true", help="Long listing format")
+parser.add_argument("-a", "--all", action="store_true", help="Include hidden files")
+
+args = parser.parse_args()
+
+file_paths = args.paths
+show_long = args.longList
+show_all = args.all
+
+def format_permissions(mode):
+    return stat.filemode(mode)
+
+for input_path in file_paths:
+    try:
+        if not os.path.exists(input_path):
+            raise FileNotFoundError(f'No such file or directory: {input_path}')
+        
+        if os.path.isfile(input_path):
+            if show_long:
+                file_stat = os.stat(input_path)
+                perms = format_permissions(file_stat.st_mode)
+                size = str(file_stat.st_size).rjust(6)
+                print(f"{perms}  {size}  {input_path}")
+            else:
+                print(input_path)
+
+        elif os.path.isdir(input_path):
+            entries = os.listdir(input_path)
+            if not show_all:
+                entries = [e for e in entries if not e.startswith(".")]
+
+            for entry in entries:
+                full_path = os.path.join(input_path, entry)
+                entry_stat = os.stat(full_path)
+                if show_long:
+                    perms = format_permissions(entry_stat.st_mode)
+                    size = str(entry_stat.st_size).rjust(6)
+                    print(f"{perms}  {size}  {entry}")
+                else:
+                    print(entry)
+
+    except Exception as e:
+        print(f'Error reading "{input_path}": {e}', file=sys.stderr)
+        sys.exit(1)

implement-shell-tools/wc/my_wc.py

@@ -0,0 +1,78 @@
+import os
+import sys
+import argparse
+
+# CLI argument parsing
+parser = argparse.ArgumentParser(description="Simplified implementation of wc")
+parser.add_argument("paths", nargs="*", default=["."], help="One or more file or directory paths")
+parser.add_argument("-l", "--line", action="store_true", help="Count lines")
+parser.add_argument("-w", "--word", action="store_true", help="Count words")
+parser.add_argument("-c", "--character", action="store_true", help="Count characters")
+
+args = parser.parse_args()
+file_paths = args.paths
+
+# Fallback: if no options passed, show all
+show_line = args.line
+show_word = args.word
+show_char = args.character
+show_all = not (show_line or show_word or show_char)
+
+# Count content in a string
+def count_content(content):
+    lines = content.splitlines()
+    words = content.strip().split()
+    characters = len(content)
+    return len(lines), len(words), characters
+
+# Totals for multiple files
+total = {
+    "lines": 0,
+    "words": 0,
+    "characters": 0
+}
+
+file_count = 0
+
+for input_path in file_paths:
+    try:
+        if os.path.isdir(input_path):
+            print(f"{input_path} is a directory. Skipping.")
+            continue
+
+        with open(input_path, "r", encoding="utf-8") as f:
+            content = f.read()
+
+        lines, words, characters = count_content(content)
+
+        total["lines"] += lines
+        total["words"] += words
+        total["characters"] += characters
+        file_count += 1
+
+        # Prepare output per file
+        output_parts = []
+        if show_line or show_all:
+            output_parts.append(f"{lines:8}")
+        if show_word or show_all:
+            output_parts.append(f"{words:8}")
+        if show_char or show_all:
+            output_parts.append(f"{characters:8}")
+
+        output_parts.append(input_path)
+        print(" ".join(output_parts))
+
+    except Exception as e:
+        print(f'Error reading "{input_path}": {e}', file=sys.stderr)
+
+# Print totals if more than one file processed
+if file_count > 1:
+    output_parts = []
+    if show_line or show_all:
+        output_parts.append(f"{total['lines']:8}")
+    if show_word or show_all:
+        output_parts.append(f"{total['words']:8}")
+    if show_char or show_all:
+        output_parts.append(f"{total['characters']:8}")
+    output_parts.append("total")
+    print(" ".join(output_parts))