python-进程(2)管理进程

subprocess
特点：
    调用外部系统命令创建新的子进程
    能够使用input/output/error
    有返回值
     可以替代旧的os.system,os.popen,commands
import subprocess
ping = subprocess.Popen(args="ping -c 4 )
print ping.pid
print ping.returncode


import subprocess
ping = subprocess.Popen(args="ping -c 4 )
print ping.pid
print ping.returncode
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使用wait()对进程进行控制，等待子进程执行完毕，在执行下面的语句
import subprocess
ping = subprocess.Popen(args="ping -c 4 )
ping.wait()
print ping.pid
print ping.returncode

PING (115.239.210.26) 56(84) bytes of data.
64 bytes from 115.239.210.26: icmp_req=1 ttl=127 time=32.0 ms
64 bytes from 115.239.210.26: icmp_req=2 ttl=127 time=33.9 ms
64 bytes from 115.239.210.26: icmp_req=3 ttl=127 time=31.7 ms
64 bytes from 115.239.210.26: icmp_req=4 ttl=127 time=31.0 ms

--- ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 25266ms
rtt min/avg/max/mdev = 31.013/32.192/33.903/1.061 ms
2754
0

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stdout/stdin/stderr

import subprocess
ping = subprocess.Popen(args="ping -c 4 )
ping.wait()
print ping.stdout.read()
print ping.pid
print ping.returncode
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