Implementing shell tools: cat, ls, and wc. in Python.

Author: Emilianouz

implement-shell-tools/cat/cat-python.py

@@ -0,0 +1,42 @@
+import sys
+
+def cat_file(filename, flag):
+    try:
+        with open(filename, 'r') as file:
+            if not flag:
+                for line in file:
+                    print(line, end="")
+
+            elif flag == "-n":
+                for index, line in enumerate(file, start=1):
+                    print(f"{index:6}\t{line}", end="")
+
+            elif flag == "-b":
+                line_number = 1
+                for line in file:
+                    if line.strip() == "":
+                        print(line, end="")
+                    else:
+                        print(f"{line_number:6}\t{line}", end="")
+                        line_number += 1
+
+    except FileNotFoundError:
+        print(f"cat: {filename}: No such file or directory", file=sys.stderr)
+    
+def main():
+    args = sys.argv[1:]
+
+    flag = False 
+    
+    if "-n" in args:
+        flag = "-n"
+        args.remove("-n")
+    elif "-b" in args:
+        flag = "-b"
+        args.remove("-b")
+
+    for filename in args:
+        cat_file(filename, flag)
+
+if __name__ == "__main__":
+    main()

implement-shell-tools/ls/ls-python.py

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+import sys
+import os
+
+def main():
+    args = sys.argv[1:]
+    
+    path = "."
+    one_per_line = False
+    show_hidden = False
+    
+    for arg in args:
+        if arg == "-a":
+            show_hidden = True
+        elif arg == "-1":
+            one_per_line = True
+        elif not arg.startswith("-"):
+            path = arg
+
+    entries = os.listdir(path)
+
+    entries.sort()
+
+    if not show_hidden:
+        entries = [f for f in entries if not f.startswith(".")]
+    
+    if one_per_line:
+        for entry in entries:
+            print(entry)
+    else:
+        print(" ".join(entries))
+
+if __name__ == "__main__":
+    main()

implement-shell-tools/wc/wc-python.py

@@ -0,0 +1,66 @@
+import sys
+
+def count_file(filename):
+   
+    with open(filename, 'r') as file:
+        content = file.read()
+    
+    lines = len(content.splitlines())
+    words = len(content.split())
+    chars = len(content)
+    
+    return (lines, words, chars)
+  
+
+def format_output(lines, words, chars, filename, show_l, show_w, show_c):
+    parts = []
+    
+    if show_l:
+        parts.append(f"{lines:8}")
+    if show_w:
+        parts.append(f"{words:8}")
+    if show_c:
+        parts.append(f"{chars:8}")
+    
+    parts.append(filename)
+    
+    return " ".join(parts)
+
+def main():
+    args = sys.argv[1:]
+    
+    l = w = c = False
+    files = []
+    
+    for arg in args:
+        if arg == "-l":
+            l = True
+        elif arg == "-w":
+            w = True
+        elif arg == "-c":
+            c = True
+        elif not arg.startswith("-"):
+            files.append(arg)
+    
+    if not (l or w or c):
+        l = w = c = True
+
+    total_lines = total_words = total_chars = 0
+    processed_files = 0
+    
+    for filename in files:
+        result = count_file(filename)
+        if result:
+            lines, words, chars = result
+            print(format_output(lines, words, chars, filename, l, w, c))
+            
+            total_lines += lines
+            total_words += words
+            total_chars += chars
+            processed_files += 1
+    
+    if processed_files > 1:
+        print(format_output(total_lines, total_words, total_chars, "total", l, w, c))
+
+if __name__ == "__main__":
+    main()