我如何在Python中命名一个外部命令,就好像我把它写在一个<unk>或命令中?


当前回答

在Python 3.5+中使用子过程,以下是我在Linux上做的技巧:

import subprocess

# subprocess.run() returns a completed process object that can be inspected
c = subprocess.run(["ls", "-ltrh"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
print(c.stdout.decode('utf-8'))

正如文档中提到的那样,PIPE 值是比特序列,为了正确显示它们,应考虑解码。

上述代码的结果是:

total 113M
-rwxr-xr-x  1 farzad farzad  307 Jan 15  2018 vpnscript
-rwxrwxr-x  1 farzad farzad  204 Jan 15  2018 ex
drwxrwxr-x  4 farzad farzad 4.0K Jan 22  2018 scripts
.... # Some other lines

其他回答

>>> from subprocess import run
>>> from shlex import split
>>> completed_process = run(split('python --version'))
Python 3.8.8
>>> completed_process
CompletedProcess(args=['python', '--version'], returncode=0)

下面是最简单的使用的例子 - 它正如所要求的那样:

>>> from subprocess import run
>>> from shlex import split
>>> completed_process = run(split('python --version'))
Python 3.8.8
>>> completed_process
CompletedProcess(args=['python', '--version'], returncode=0)

>>> completed_process.args
['python', '--version']
>>> completed_process.returncode
0

如果您想捕获输出,您可以将 subprocess.PIPE 转移到适当的 stderr 或 stdout:

>>> from subprocess import PIPE
>>> completed_process = run(shlex.split('python --version'), stdout=PIPE, stderr=PIPE)
>>> completed_process.stdout
b'Python 3.8.8\n'
>>> completed_process.stderr
b''

相应的属性返回比特。

>>> import textwrap
>>> args = ['python', textwrap.__file__]
>>> cp = run(args, stdout=subprocess.PIPE)
>>> cp.stdout
b'Hello there.\n  This is indented.\n'

下面是源头的真实签名,如助(run)所示:

输入可以是一个字符串(或单码,如果指定编码或 universal_newlines=True)将被带到子过程的stdin。

这个 check=true 的例子比我可以看到的更好:

波恩


def __init__(self, args, bufsize=-1, executable=None,
             stdin=None, stdout=None, stderr=None,
             preexec_fn=None, close_fds=True,
             shell=False, cwd=None, env=None, universal_newlines=None,
             startupinfo=None, creationflags=0,
             restore_signals=True, start_new_session=False,
             pass_fds=(), *, user=None, group=None, extra_groups=None,
             encoding=None, errors=None, text=None, umask=-1, pipesize=-1):

了解Popen的剩余文档将作为读者的练习留下来。

使用:

import subprocess

p = subprocess.Popen("df -h", shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()[0]
print p.split("\n")

它提供良好的产量,更容易与:

['Filesystem      Size  Used Avail Use% Mounted on',
 '/dev/sda6        32G   21G   11G  67% /',
 'none            4.0K     0  4.0K   0% /sys/fs/cgroup',
 'udev            1.9G  4.0K  1.9G   1% /dev',
 'tmpfs           387M  1.4M  386M   1% /run',
 'none            5.0M     0  5.0M   0% /run/lock',
 'none            1.9G   58M  1.9G   3% /run/shm',
 'none            100M   32K  100M   1% /run/user',
 '/dev/sda5       340G  222G  100G  69% /home',
 '']

在 Windows 中,您只能输入子过程模块并运行外部命令,以下列方式呼叫 subprocess.Popen(), subprocess.Popen().communicate() 和 subprocess.Popen().wait():

# Python script to run a command line
import subprocess

def execute(cmd):
    """
        Purpose  : To execute a command and return exit status
        Argument : cmd - command to execute
        Return   : exit_code
    """
    process = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    (result, error) = process.communicate()

    rc = process.wait()

    if rc != 0:
        print "Error: failed to execute command:", cmd
        print error
    return result
# def

command = "tasklist | grep python"
print "This process detail: \n", execute(command)

出口:

This process detail:
python.exe                     604 RDP-Tcp#0                  4      5,660 K

Invoke 是一个 Python (2.7 和 3.4+) 任务执行工具和图书馆. 它提供清洁,高级别的 API 运行 Shell 命令:

>>> from invoke import run
>>> cmd = "pip install -r requirements.txt"
>>> result = run(cmd, hide=True, warn=True)
>>> print(result.ok)
True
>>> print(result.stdout.splitlines()[-1])
Successfully installed invocations-0.13.0 pep8-1.5.7 spec-1.3.1

在Python 3.5+中使用子过程,以下是我在Linux上做的技巧:

import subprocess

# subprocess.run() returns a completed process object that can be inspected
c = subprocess.run(["ls", "-ltrh"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
print(c.stdout.decode('utf-8'))

正如文档中提到的那样,PIPE 值是比特序列,为了正确显示它们,应考虑解码。

上述代码的结果是:

total 113M
-rwxr-xr-x  1 farzad farzad  307 Jan 15  2018 vpnscript
-rwxrwxr-x  1 farzad farzad  204 Jan 15  2018 ex
drwxrwxr-x  4 farzad farzad 4.0K Jan 22  2018 scripts
.... # Some other lines