feat: implement cat with -n and -b flags.

Author: jamallaqdiem

implement-shell-tools/cat/cat.py

@@ -0,0 +1,41 @@
+import sys
+
+show_all_numbers = "-n" in sys.argv #  this check will return true if found the flag
+show_non_blank_numbers = "-b" in sys.argv #  this check will return true if found the flag
+
+# 2. using filter get only the filenames everything except the script name and flags
+files = [arg for arg in sys.argv[1:] if arg not in ["-n", "-b"]]
+
+if not files:
+    print("Usage: python3 cat.py [-n] [-b] <filenames>")
+    sys.exit()
+
+line_count = 1
+# 3. Process each file 
+for filename in files:
+    try:
+        with open(filename, "r") as file:
+            for line in file:
+                # Logic for -b 
+                if show_non_blank_numbers:
+                    if line.strip(): # If line is not empty
+                        print(f"{line_count:>6}\t{line}", end="")
+                        line_count += 1
+                    else:
+                       # Standard cat no flags
+                        print(line, end="")
+                
+                # Logic for -n 
+                elif show_all_numbers:
+                    print(f"{line_count:>6}\t{line}", end="")
+                    line_count += 1
+                
+                # Standard cat no flags
+                else:
+                    print(line, end="")
+                    
+    # throw clear errors                
+    except FileNotFoundError:
+        print(f"Error: {filename}: No such file or directory")
+    except IsADirectoryError:
+        print(f"Error: {filename}: Is a directory")