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())