本文共 6282 字，大约阅读时间需要 20 分钟。
我们经常需要通过Python去执行一条系统命令或脚本，系统的shell命令是独立于你的python进程之外的，每执行一条命令，就是发起一个新进程，通过python调用系统命令或脚本的模块在python2有os.system，,commands,popen2等也可以，比较乱，于是官方推出了subprocess,目地是提供统一的模块来实现对系统命令或脚本的调用
"os.system获取不到返回值">>> import os>>> a = os.system("df -h") Filesystem Size Used Avail Use% Mounted on/dev/sda3 98G 1.9G 97G 2% /devtmpfs 479M 0 479M 0% /devtmpfs 489M 0 489M 0% /dev/shmtmpfs 489M 6.7M 482M 2% /runtmpfs 489M 0 489M 0% /sys/fs/cgroup/dev/sda1 1014M 120M 895M 12% /boottmpfs 98M 0 98M 0% /run/user/0>>> a0" os.popen可以获取到返回值">>> os.popen("df -h") >>> f = os.popen("df -h")>>> f.read()'Filesystem Size Used Avail Use% Mounted on\n/dev/sda3 98G 1.9G 97G 2% /\ndevtmpfs 479M 0 479M 0% /dev\ntmpfs 489M 0 489M 0% /dev/shm\ntmpfs 489M 6.7M 482M 2% /run\ntmpfs 489M 0 489M 0% /sys/fs/cgroup\n/dev/sda1 1014M 120M 895M 12% /boot\ntmpfs 98M 0 98M 0% /run/user/0\n'"python2中的commands模块">>> import commands>>> commands.getstatusoutput("df -h")(0, 'Filesystem Size Used Avail Use% Mounted on\n/dev/sda3 98G 1.8G 97G 2% /\ndevtmpfs 479M 0 479M 0% /dev\ntmpfs 489M 0 489M 0% /dev/shm\ntmpfs 489M 6.7M 482M 2% /run\ntmpfs 489M 0 489M 0% /sys/fs/cgroup\n/dev/sda1 1014M 120M 895M 12% /boot\ntmpfs 98M 0 98M 0% /run/user/0') subprocess.run(*popenargs, input=None, timeout=None, check=False, **kwargs) #官方推荐subprocess.call(*popenargs, timeout=None, **kwargs) #跟上面实现的内容差不多，另一种写法subprocess.Popen() #上面各种方法的底层封装
"subprocess.run">>> a = subprocess.run(["df","-h"])Filesystem Size Used Avail Use% Mounted on/dev/sda3 98G 2.3G 96G 3% /devtmpfs 479M 0 479M 0% /devtmpfs 489M 0 489M 0% /dev/shmtmpfs 489M 6.8M 482M 2% /runtmpfs 489M 0 489M 0% /sys/fs/cgroup/dev/sda1 1014M 120M 895M 12% /boottmpfs 98M 0 98M 0% /run/user/0>>> a.args['df', '-h']>>> a.returncode0>>> a.check_returncode()>>> a = subprocess.run(["df","-h"],stdout=subprocess.PIPE,stderr=subprocess.PIPE)>>> a.stdoutb'Filesystem Size Used Avail Use% Mounted on\n/dev/sda3 98G 2.3G 96G 3% /\ndevtmpfs 479M 0 479M 0% /dev\ntmpfs 489M 0 489M 0% /dev/shm\ntmpfs 489M 6.8M 482M 2% /run\ntmpfs 489M 0 489M 0% /sys/fs/cgroup\n/dev/sda1 1014M 120M 895M 12% /boot\ntmpfs 98M 0 98M 0% /run/user/0\n'>>> a.stderrb''>>> a = subprocess.run(["dsf","-h"],stdout=subprocess.PIPE,stderr=subprocess.PIPE)Traceback (most recent call last): File "", line 1, in File "/usr/local/python3Dir/lib/python3.6/subprocess.py", line 403, in run with Popen(*popenargs, **kwargs) as process: File "/usr/local/python3Dir/lib/python3.6/subprocess.py", line 709, in __init__ restore_signals, start_new_session) File "/usr/local/python3Dir/lib/python3.6/subprocess.py", line 1344, in _execute_child raise child_exception_type(errno_num, err_msg, err_filename)FileNotFoundError: [Errno 2] No such file or directory: 'dsf': 'dsf'>>> a = subprocess.run(["df","-h","|","grep","a"],stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)>>> a.stdout b'Filesystem 1K-blocks Used Available Use% Mounted on\n/dev/sda3 102709252 2337100 100372152 3% /\ndevtmpfs 490020 0 490020 0% /dev\ntmpfs 499848 0 499848 0% /dev/shm\ntmpfs 499848 6900 492948 2% /run\ntmpfs 499848 0 499848 0% /sys/fs/cgroup\n/dev/sda1 1038336 121872 916464 12% /boot\ntmpfs 99972 0 99972 0% /run/user/0\n'
"subprocess.call">>> a = subprocess.call(["df","-h"])Filesystem Size Used Avail Use% Mounted on/dev/sda3 98G 2.3G 96G 3% /devtmpfs 479M 0 479M 0% /devtmpfs 489M 0 489M 0% /dev/shmtmpfs 489M 6.8M 482M 2% /runtmpfs 489M 0 489M 0% /sys/fs/cgroup/dev/sda1 1014M 120M 895M 12% /boottmpfs 98M 0 98M 0% /run/user/0>>>
"subprocess.Popen会发起新的进程，不影响主进程">>> a = subprocess.Popen("sleep 10",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)#10秒后返回>>> a = subprocess.Popen("sleep 10",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)#立刻返回，poll()可以用来监控命令是否结束>>> a.poll()>>> a.poll()>>> a.poll()0 "运行函数">>> def sayhi(): print("hello")... ... >>> sayhi()hello>>> a = subprocess.Popen("echo $PWD",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True,preexec_fn=sayhi)>>> a.stdout.read()b'hello\n/usr/local/python3/Python-3.6.3\n'>>> >>> a = subprocess.Popen("echo $PWD",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True,cwd="/tmp",preexec_fn=sayhi)>>> a.stdout.read()b'hello\n/tmp\n'>>> >>> a = subprocess.Popen("echo $PWD;sleep 15",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True,cwd="/tmp",preexec_fn=sayhi)>>> a.wait() #等在这里直到上面的程序运行完成0>>> "Popen程序的终止">>> a = subprocess.Popen("echo $PWD;sleep 100",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)>>> a.terminate()#程序的终止>>> a.kill())#程序的终止>>> >>> import signal>>> a = subprocess.Popen("echo $PWD;sleep 100",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)>>> a.send_signal(signal.SIGKILL) "communicate()程序交互，只能交互一次,再次交互会报错">>> import subprocess>>> a = subprocess.Popen("python3 guessage.py",stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)>>> a.communicate(b'33')(b'input the age of you think:you should input one number!\ninput the age of you think:you should input one number!\ninput the age of you think:you should input one number!\n', b'')>>> >>> a.communicate(b'12')Traceback (most recent call last): File " ", line 1, in File "/usr/local/python3Dir/lib/python3.6/subprocess.py", line 818, in communicate raise ValueError("Cannot send input after starting communication")ValueError: Cannot send input after starting communication>>> 转载于:https://blog.51cto.com/10983441/2389979