Build and Assemble a program to print a message, using python (self contained script)

nasm_message.py

import subprocess
asm_code = """
	.global _start

	.text

_start:
	mov 	$1,%rax
	mov	$1,%rdi
	mov	$msg, %rsi
	mov	$?size?, %rdx
	syscall

	mov	$60, %rax
	xor	%rdi,%rdi
	syscall

msg:
	.ascii "?message?"
"""
with open("_main.s","w") as _code:
	_code.write(asm_code)

line = raw_input("Message:")
sz = len(line)
with open("_main.s","r") as f:
	data = f.read()
	result = data.replace("?size?",str(sz))
	result = result.replace("?message?",line.replace("\n",''))
	with open("patch_main.s","w") as _out:
		_out.write(result)
subprocess.call(["gcc","-c","patch_main.s","-o","patch.o"])
subprocess.call(["ld","patch.o","-o","app"])
print("Complete")