program Read_And_Store_A_File;

var Read_File        : text;

    Input_File_Name  : string[12];

    Write_File       : text;

    Output_File_Name : string[12];

    Line_Number      : integer;

    Big_String       : string[80];

    Read_File_OK     : boolean;
begin

   Write('Enter input file name ');

   Readln(Input_File_Name);

   Assign(Read_File,Input_File_Name);

   {$I-}

   Reset(Read_File);

   {$I+}

   Read_File_OK := (IOResult = 0);

   if Read_File_OK then begin

      Write('Enter output file name ');

      Readln(Output_File_Name);

      Assign(Write_File,Output_File_Name);

      Rewrite(Write_File);
      Line_Number := 1;

      while not Eof(Read_File) do begin

         Readln(Read_File,Big_String);

         Write(Write_File,Line_Number:5,'  ');

         Writeln(Write_File,Big_String);

         Line_Number := Line_Number + 1;

      end;

      Close(Read_File);

      Close(Write_File);

   end

   else

      Writeln('Input file doesn''t exist, execution aborted');

end.  (* of program *)


Result of execution

(The selected file is copied to the selected output file)