我想编写一个函数,该函数将执行shell命令并将其输出作为字符串返回,无论它是错误消息还是成功消息。我只想得到和用命令行得到的相同的结果。

什么样的代码示例可以做到这一点呢?

例如:

def run_command(cmd):
    # ??????

print run_command('mysqladmin create test -uroot -pmysqladmin12')
# Should output something like:
# mysqladmin: CREATE DATABASE failed; error: 'Can't create database 'test'; database exists'

当前回答

可以将输出重定向到文本文件,然后将其读回来。

import subprocess
import os
import tempfile

def execute_to_file(command):
    """
    This function execute the command
    and pass its output to a tempfile then read it back
    It is usefull for process that deploy child process
    """
    temp_file = tempfile.NamedTemporaryFile(delete=False)
    temp_file.close()
    path = temp_file.name
    command = command + " > " + path
    proc = subprocess.run(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
    if proc.stderr:
        # if command failed return
        os.unlink(path)
        return
    with open(path, 'r') as f:
        data = f.read()
    os.unlink(path)
    return data

if __name__ == "__main__":
    path = "Somepath"
    command = 'ecls.exe /files ' + path
    print(execute(command))

其他回答

可以将输出重定向到文本文件,然后将其读回来。

import subprocess
import os
import tempfile

def execute_to_file(command):
    """
    This function execute the command
    and pass its output to a tempfile then read it back
    It is usefull for process that deploy child process
    """
    temp_file = tempfile.NamedTemporaryFile(delete=False)
    temp_file.close()
    path = temp_file.name
    command = command + " > " + path
    proc = subprocess.run(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
    if proc.stderr:
        # if command failed return
        os.unlink(path)
        return
    with open(path, 'r') as f:
        data = f.read()
    os.unlink(path)
    return data

if __name__ == "__main__":
    path = "Somepath"
    command = 'ecls.exe /files ' + path
    print(execute(command))

如果你使用subprocess python模块,你可以分别处理命令的STDOUT、STDERR和返回码。您可以看到完整命令调用器实现的示例。当然你可以用try.扩展它,除非你想。

下面的函数返回STDOUT, STDERR和Return代码,以便您可以在另一个脚本中处理它们。

import subprocess

def command_caller(command=None)
    sp = subprocess.Popen(command, stderr=subprocess.PIPE, stdout=subprocess.PIPE, shell=False)
    out, err = sp.communicate()
    if sp.returncode:
        print(
            "Return code: %(ret_code)s Error message: %(err_msg)s"
            % {"ret_code": sp.returncode, "err_msg": err}
            )
    return sp.returncode, out, err

这里有一个解决方案,如果你想在进程运行或不运行时打印输出。


我还添加了当前工作目录,这对我来说很有用不止一次。


希望这个解决方案能帮助到别人:)。

import subprocess

def run_command(cmd_and_args, print_constantly=False, cwd=None):
"""Runs a system command.

:param cmd_and_args: the command to run with or without a Pipe (|).
:param print_constantly: If True then the output is logged in continuous until the command ended.
:param cwd: the current working directory (the directory from which you will like to execute the command)
:return: - a tuple containing the return code, the stdout and the stderr of the command
"""
output = []

process = subprocess.Popen(cmd_and_args, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, cwd=cwd)

while True:
    next_line = process.stdout.readline()
    if next_line:
        output.append(str(next_line))
        if print_constantly:
            print(next_line)
    elif not process.poll():
        break

error = process.communicate()[1]

return process.returncode, '\n'.join(output), error

如果您需要在多个文件上运行shell命令,这对我来说很有用。

import os
import subprocess

# Define a function for running commands and capturing stdout line by line
# (Modified from Vartec's solution because it wasn't printing all lines)
def runProcess(exe):    
    p = subprocess.Popen(exe, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    return iter(p.stdout.readline, b'')

# Get all filenames in working directory
for filename in os.listdir('./'):
    # This command will be run on each file
    cmd = 'nm ' + filename

    # Run the command and capture the output line by line.
    for line in runProcess(cmd.split()):
        # Eliminate leading and trailing whitespace
        line.strip()
        # Split the output 
        output = line.split()

        # Filter the output and print relevant lines
        if len(output) > 2:
            if ((output[2] == 'set_program_name')):
                print filename
                print line

编辑:刚刚看到Max Persson的解决方案和J.F. Sebastian的建议。继续把它整合进去。

我在Python 2.6.5的Windows上尝试了@senderle对Vartec解决方案的旋转,但我得到了错误,没有其他解决方案有效。我的错误是:WindowsError:[错误6]句柄无效。

我发现我必须将PIPE分配给每个句柄,以使它返回我所期望的输出——下面的方法对我有用。

import subprocess

def run_command(cmd):
    """given shell command, returns communication tuple of stdout and stderr"""
    return subprocess.Popen(cmd, 
                            stdout=subprocess.PIPE, 
                            stderr=subprocess.PIPE, 
                            stdin=subprocess.PIPE).communicate()

然后像这样调用,([0]获取元组的第一个元素,stdout):

run_command('tracert 11.1.0.1')[0]

在了解了更多信息后,我认为我需要这些管道参数,因为我正在开发一个使用不同句柄的自定义系统,因此我必须直接控制所有std。

要停止控制台弹出窗口(Windows),请执行以下操作:

def run_command(cmd):
    """given shell command, returns communication tuple of stdout and stderr"""
    # instantiate a startupinfo obj:
    startupinfo = subprocess.STARTUPINFO()
    # set the use show window flag, might make conditional on being in Windows:
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
    # pass as the startupinfo keyword argument:
    return subprocess.Popen(cmd,
                            stdout=subprocess.PIPE, 
                            stderr=subprocess.PIPE, 
                            stdin=subprocess.PIPE, 
                            startupinfo=startupinfo).communicate()

run_command('tracert 11.1.0.1')