import sys
if len(sys.argv) != 4:
print(f"usage: {sys.argv[0]} from-string to-string filename")
exit(1)
from_string = sys.argv[1].replace("\\n", "\n")
to_string = sys.argv[2].replace("\\n", "\n")
with open(sys.argv[3]) as f:
new_text = f.read().replace(from_string, to_string)
with open(sys.argv[3], "w") as f:
f.write(new_text)