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import subprocess
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3

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def runcmd(command):
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    ret = subprocess.run(command,  # 子进程要执行的命令
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                         shell=True,  # 执行的是shell的命令
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                         stdout=subprocess.PIPE,
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                         stderr=subprocess.PIPE,
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                         encoding="utf-8",
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                         timeout=1)
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    # returncode属性是run()函数返回结果的状态。
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    if ret.returncode == 0:
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        print("success:", ret)
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    else:
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        print("error:", ret)
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runcmd(["dir", "/b"])  # 序列参数
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# success: CompletedProcess(args=['dir', '/b'], returncode=0, stderr='')
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runcmd("exit 1")  # 字符串参数
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# error: CompletedProcess(args='exit 1', returncode=1, stdout='', stderr='')

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class Popen:
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    """ Execute a child program in a new process.
3

4
    For a complete description of the arguments see the Python documentation.
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    Arguments:
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      args: A string, or a sequence of program arguments.
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      bufsize: supplied as the buffering argument to the open() function when
10
          creating the stdin/stdout/stderr pipe file objects
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      executable: A replacement program to execute.
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      stdin, stdout and stderr: These specify the executed programs' standard
15
          input, standard output and standard error file handles, respectively.
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      preexec_fn: (POSIX only) An object to be called in the child process
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          just before the child is executed.
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      close_fds: Controls closing or inheriting of file descriptors.
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      shell: If true, the command will be executed through the shell.
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      cwd: Sets the current directory before the child is executed.
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      env: Defines the environment variables for the new process.
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      text: If true, decode stdin, stdout and stderr using the given encoding
29
          (if set) or the system default otherwise.
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      universal_newlines: Alias of text, provided for backwards compatibility.
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      startupinfo and creationflags (Windows only)
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      restore_signals (POSIX only)
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      start_new_session (POSIX only)
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      group (POSIX only)
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      extra_groups (POSIX only)
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      user (POSIX only)
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      umask (POSIX only)
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      pass_fds (POSIX only)
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      encoding and errors: Text mode encoding and error handling to use for
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          file objects stdin, stdout and stderr.
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    Attributes:
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        stdin, stdout, stderr, pid, returncode
54
    """
55
    _child_created = False  # Set here since __del__ checks it
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    def __init__(self, args, bufsize=-1, executable=None,
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                 stdin=None, stdout=None, stderr=None,
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                 preexec_fn=None, close_fds=True,
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                 shell=False, cwd=None, env=None, universal_newlines=None,
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                 startupinfo=None, creationflags=0,
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                 restore_signals=True, start_new_session=False,
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                 pass_fds=(), *, user=None, group=None, extra_groups=None,
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                 encoding=None, errors=None, text=None, umask=-1, pipesize=-1):
65
        ...

1
import subprocess
2

3
p = subprocess.Popen('ls -l', shell=True)
4

5

6
# Popen的对象所具有的方法：
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#       poll(): 检查进程是否终止，如果终止则返回 returncode，否则返回 None。
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#       wait(timeout): 等待子进程终止。
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#       communicate(input,timeout): 和子进程交互，发送和读取数据。
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#       send_signal(singnal): 发送信号到子进程 。
11
#       terminate(): 停止子进程,也就是发送SIGTERM信号到子进程。
12
#       kill(): 杀死子进程。发送 SIGKILL 信号到子进程。
13

14
def f(command):
15
    # 创建一个子进程，并且执行
16
    res_subprocess = subprocess.Popen(command,
17
                                      shell=True,
18
                                      stdout=subprocess.PIPE,
19
                                      stderr=subprocess.PIPE,
20
                                      encoding="utf-8")
21
    # 这里是用wait()方法，等待子进程结束。
22
    res_subprocess.wait(2)
23
    if res_subprocess.poll() == 0:
24
        print(res_subprocess.communicate()[1])
25
    else:
26
        print("失败")
27

28

29
f("python --version")
30
f("exit 1")