import sys inFile = sys.argv[1] outFile = sys.argv[2] # inFile = 'simple.in' # outFile = 'simple.out' with open(inFile, 'r', encoding='utf-8') as inputFile, open(outFile, 'w', encoding='utf-8') as outputFile: for line in inputFile: if 'hamlet' in line.lower(): outputFile.write(line) # print(line, end='')