London | 26-JUL-SDC | Ping Wang | Sprint 4 | Implement-shell-tools

implement-shell-tools/cat/cat.py

@@ -0,0 +1,33 @@
+import sys
+
+args = sys.argv[1:]
+
+number_all = "-n" in args
+number_nonblank = "-b" in args
+
+files = [arg for arg in args if arg not in ("-n", "-b")]
+
+line_number = 1
+
+for filename in files:
+    try:
+        with open(filename, "r") as file:
+            content = file.read()
+
+            lines = content[:-1].split("\n") if content.endswith("\n") else content.split("\n")
+
+            for line in lines:
+                if number_all:
+                    print(f"{line_number:6}\t{line}")
+                    line_number += 1
+
+                elif number_nonblank and line != "":
+                    print(f"{line_number:6}\t{line}")
+                    line_number += 1
+
+                else:
+                    print(line)
+
+    except Exception as err:
+        print(f"cat: {filename}: {err}")
+

implement-shell-tools/ls/ls.py

@@ -0,0 +1,48 @@
+import sys
+import os
+
+args = sys.argv[1:]
+
+one_line = False
+show_hidden = False
+targets = []
+
+for arg in args:
+    if arg == "-1":
+        one_line = True
+    elif arg == "-a":
+        show_hidden = True
+    else:
+        targets.append(arg)
+
+if len(targets) == 0:
+    targets.append(".")
+
+
+def list_directory(directory):
+    files = os.listdir(directory)
+
+    if not show_hidden:
+        files = [file for file in files if not file.startswith(".")]
+
+    files.sort()
+
+    if one_line:
+        print("\n".join(files))
+    else:
+        print("  ".join(files))
+
+
+def list_target(target):
+    try:
+        if os.path.isdir(target):
+            list_directory(target)
+        else:
+            print(target)
+
+    except Exception:
+        print(f"ls: cannot access '{target}': No such file or directory")
+
+
+for target in targets:
+    list_target(target)

implement-shell-tools/wc/wc.py

@@ -0,0 +1,84 @@
+import sys
+
+args = sys.argv[1:]
+
+count_lines = False
+count_words = False
+count_bytes = False
+files = []
+
+for arg in args:
+    if arg == "-l":
+        count_lines = True
+    elif arg == "-w":
+        count_words = True
+    elif arg == "-c":
+        count_bytes = True
+    else:
+        files.append(arg)
+
+# If no flags are given, wc shows all three
+if not count_lines and not count_words and not count_bytes:
+    count_lines = True
+    count_words = True
+    count_bytes = True
+
+def print_output(lines, words, bytes_count, label):
+    output = []
+
+    if count_lines:
+        output.append(f"{lines:8}")
+
+    if count_words:
+        output.append(f"{words:8}")
+
+    if count_bytes:
+        output.append(f"{bytes_count:8}")
+
+    output.append(f" {label}")
+
+    print("".join(output))
+
+
+def count_file(filename):
+    try:
+        with open(filename, "r") as file:
+            content = file.read()
+
+        lines = content.count("\n")
+
+        words = 0 if content.strip() == "" else len(content.split())
+
+        # UTF-8 bytes, same idea as Buffer.byteLength()
+        bytes_count = len(content.encode("utf-8"))
+
+        print_output(lines, words, bytes_count, filename)
+
+        return {
+            "lines": lines,
+            "words": words,
+            "bytes": bytes_count
+        }
+
+    except Exception as err:
+        print(f"wc: {filename}: {err}")
+        return None
+
+
+total_lines = 0
+total_words = 0
+total_bytes = 0
+
+
+
+for file in files:
+    counts = count_file(file)
+
+    if counts:
+        total_lines += counts["lines"]
+        total_words += counts["words"]
+        total_bytes += counts["bytes"]
+
+
+if len(files) > 1:
+    print_output(total_lines, total_words, total_bytes, "total")