python中使用subprocess调用SAC

import subprocess

p=subprocess.Popen(['sac'],stdin=subprocess.PIPE)
s=""
s+="echo on \n"
s+="r *.D.SAC\n"
s+="rmean\n"
s+="rtr\n"
s+="taper\n"
s+="bp co 0.5 12 n 4 p 2\n"
s+="decimate 4\n"
s+="w over\n"
s+="q\n"
p.communicate(s.encode())