ZA | 25-SDC-July | Luke Manyamazi | Sprint 4 | Python Implement Shell Tools Exercises

implement-shell-tools/cat/cat.py

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+import argparse
+import sys
+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="")
+
+
+def cat(filepath, numbering, start_line):
+    line_number = start_line
+
+    try:
+        with open(filepath) as file:
+            for line in file:
+                should_number = (
+                    numbering == Numbering.ALL
+                    or (
+                        numbering == Numbering.NONEMPTY
+                        and line.strip("\n")
+                    )
+                )
+
+                if should_number:
+                    print_numbered_line(line, line_number)
+                    line_number += 1
+                else:
+                    print(line, end="")
+
+    except FileNotFoundError:
+        print(
+            f"cat: {filepath}: No such file or directory",
+            file=sys.stderr,
+        )
+        return line_number, False
+
+    except IsADirectoryError:
+        print(
+            f"cat: {filepath}: Is a directory",
+            file=sys.stderr,
+        )
+        return line_number, False
+
+    except PermissionError:
+        print(
+            f"cat: {filepath}: Permission denied",
+            file=sys.stderr,
+        )
+        return line_number, False
+
+    return line_number, True
+
+
+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
+    success = True
+
+    for filepath in args.files:
+        line_number, file_success = cat(
+            filepath,
+            numbering=numbering,
+            start_line=line_number,
+        )
+        success = success and file_success
+
+    return 0 if success else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())

implement-shell-tools/ls/ls.py

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+import argparse
+import os
+import sys
+
+
+def ls(path, one_column, show_hidden):
+    try:
+        if os.path.isfile(path):
+            print(os.path.basename(path))
+            return True
+
+        files = os.listdir(path)
+
+        if show_hidden:
+            files = [".", ".."] + files
+        else:
+            files = [file for file in files if not file.startswith(".")]
+
+        files.sort()
+
+        separator = "\n" if one_column else "\t"
+        print(*files, sep=separator)
+
+        return True
+
+    except FileNotFoundError:
+        print(
+            f"ls: cannot access '{path}': No such file or directory",
+            file=sys.stderr,
+        )
+    except NotADirectoryError:
+        print(
+            f"ls: cannot access '{path}': Not a directory",
+            file=sys.stderr,
+        )
+    except PermissionError:
+        print(
+            f"ls: cannot open directory '{path}': Permission denied",
+            file=sys.stderr,
+        )
+
+    return False
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="List directory contents."
+    )
+
+    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()
+
+    success = ls(
+        path=args.path,
+        one_column=args.one_column,
+        show_hidden=args.a,
+    )
+
+    return 0 if success else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())

implement-shell-tools/wc/wc.py

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+import argparse
+import sys
+
+
+def wc(path):
+    try:
+        with open(path, "rb") as file:
+            content = file.read()
+
+        line_count = content.count(b"\n")
+        word_count = len(content.split())
+        byte_count = len(content)
+
+        return line_count, word_count, byte_count
+
+    except FileNotFoundError:
+        print(
+            f"wc: {path}: No such file or directory",
+            file=sys.stderr,
+        )
+    except IsADirectoryError:
+        print(
+            f"wc: {path}: Is a directory",
+            file=sys.stderr,
+        )
+    except PermissionError:
+        print(
+            f"wc: {path}: Permission denied",
+            file=sys.stderr,
+        )
+    except OSError as error:
+        print(
+            f"wc: {path}: {error}",
+            file=sys.stderr,
+        )
+
+    return None
+
+
+def print_stats(
+    line_count,
+    word_count,
+    byte_count,
+    filename,
+    show_lines,
+    show_words,
+    show_bytes,
+):
+    parts = []
+
+    if show_lines:
+        parts.append(f"{line_count:7d}")
+
+    if show_words:
+        parts.append(f"{word_count:7d}")
+
+    if show_bytes:
+        parts.append(f"{byte_count:7d}")
+
+    print("".join(parts), filename)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Print newline, word, and byte counts for files."
+    )
+
+    parser.add_argument(
+        "-l",
+        action="store_true",
+        help="print the newline count",
+    )
+
+    parser.add_argument(
+        "-w",
+        action="store_true",
+        help="print the word count",
+    )
+
+    parser.add_argument(
+        "-c",
+        action="store_true",
+        help="print the byte count",
+    )
+
+    parser.add_argument(
+        "paths",
+        nargs="+",
+        help="files to count",
+    )
+
+    args = parser.parse_args()
+
+    # If no options are supplied, wc prints all three counts.
+    show_lines = args.l
+    show_words = args.w
+    show_bytes = args.c
+
+    if not any((show_lines, show_words, show_bytes)):
+        show_lines = True
+        show_words = True
+        show_bytes = True
+
+    total_lines = 0
+    total_words = 0
+    total_bytes = 0
+    successful_files = 0
+
+    for path in args.paths:
+        counts = wc(path)
+
+        if counts is None:
+            continue
+
+        line_count, word_count, byte_count = counts
+
+        total_lines += line_count
+        total_words += word_count
+        total_bytes += byte_count
+        successful_files += 1
+
+        print_stats(
+            line_count,
+            word_count,
+            byte_count,
+            path,
+            show_lines,
+            show_words,
+            show_bytes,
+        )
+
+    if len(args.paths) > 1 and successful_files > 0:
+        print_stats(
+            total_lines,
+            total_words,
+            total_bytes,
+            "total",
+            show_lines,
+            show_words,
+            show_bytes,
+        )
+
+    return 0 if successful_files == len(args.paths) else 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())