read file and search some text in file (use chunk size)

#import module sys for get param and exit if param not exists and os for
#check if ifle exists

import sys
import os

#check param is corect when start program in prompt
if len(sys.argv) != 3:
    print("Enter file name and what search in file ")
    sys.exit()
else:
    File_Name = sys.argv[1]
    search_name = sys.argv[2]
#write how much char read when read file name
    line_len = 10


class Main:

    def __init__(self, File_Name):
        self.File_Name = File_Name
        if os.path.isfile(self.File_Name):
            self.read_file_name = open(self.File_Name).read()
            Main.read_file(self, self.read_file_name, line_len)
        else:
            print("File not found")
            sys.exit()

    def read_file(self, name_file, line_len):
        lines = self.read_file_name.split('\n')
        while lines:
            chunk = lines[:line_len]
            lines = lines[line_len:]
            for line in chunk:
                if line.startswith(search_name) or line.startswith(search_name.upper()):
                    print(line)


if __name__ == "__main__":
    main = Main(File_Name)