implementation of cat with python

Author: HilolaRustam

implement-shell-tools/.gitignore

@@ -0,0 +1 @@
+.venv/

implement-shell-tools/cat/mycat.py

@@ -13,15 +13,64 @@ def expand_paths(paths):
             files.extend(matches)
         else: 
             files.append(p) # keep as-is (will error later if missing)
-            return sorted(files)
+    return sorted(files)
 
 def read_lines(file):
            with open(file, "r", encoding="utf-8") as f:
                return f.readlines()
 
-def print_lines(files, number_lines==False, number_nonempty=False):
+def print_lines(files, number_all=False, number_nonempty=False):
     line_no = 1     
     for file in files:
-              
+        try:
+            lines = read_lines(file)
+        except FileNotFoundError:
+            print(f"cat: {file}: No such file or directory", file=sys.stderr)
+            continue
 
-            
+        for line in lines:
+            is_empty = (line.strip() == "")
+            
+            if number_nonempty:
+                if not is_empty:
+                    prefix = f"{line_no:6}\t"
+                    line_no += 1
+                else:
+                    prefix = "" 
+            elif number_all:
+                prefix = f"{line_no:6}\t"
+                line_no += 1
+            else:
+                prefix = ""
+                
+            # avoid double newlines: line already includes '\n'
+            sys.stdout.write(prefix + line)
+            
+            
+def main():
+    args = sys.argv[1:]
+    
+    if not args:
+        print("Usage: cat [-n|-b] file...", file=sys.stderr)
+        sys.exit(1)
+        
+    number_all = False
+    number_nonempty = False
+    paths = []
+    
+    for a in args:
+        if a == "-n":
+            number_all = True
+        elif a == "-b":
+            number_nonempty = True
+            number_all = False #-b overrides -n
+        else:
+            paths.append(a)
+            
+    files = expand_paths(paths)
+    print_lines(files, number_all,number_nonempty)
+
+    
+if __name__ == "__main__":
+    main()                                                      
+