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

Vartec的答案不读取所有的行,所以我做了一个版本:

def run_command(command):
    p = subprocess.Popen(command,
                         stdout=subprocess.PIPE,
                         stderr=subprocess.STDOUT)
    return iter(p.stdout.readline, b'')

用法与公认的答案相同:

command = 'mysqladmin create test -uroot -pmysqladmin12'.split()
for line in run_command(command):
    print(line)

其他回答

在Python 3.7+中,使用subprocess.run并传递capture_output=True:

import subprocess
result = subprocess.run(['echo', 'hello', 'world'], capture_output=True)
print(repr(result.stdout))

这将返回字节:

b'hello world\n'

如果你想把字节转换成字符串,添加text=True:

result = subprocess.run(['echo', 'hello', 'world'], capture_output=True, text=True)
print(repr(result.stdout))

这将读取字节使用您的默认编码:

'hello world\n'

如果你需要手动指定不同的编码,使用encoding="your encoding"而不是text=True:

result = subprocess.run(['echo', 'hello', 'world'], capture_output=True, encoding="utf8")
print(repr(result.stdout))

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

这要简单得多,但只适用于Unix(包括Cygwin)和Python2.7。

import commands
print commands.getstatusoutput('wc -l file')

它返回一个元组(return_value, output)。

对于在Python2和Python3中都可以工作的解决方案,请使用subprocess模块:

from subprocess import Popen, PIPE
output = Popen(["date"],stdout=PIPE)
response = output.communicate()
print response

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))

拆分子进程的初始命令可能非常棘手和麻烦。

使用shlex.split()来帮助自己。

示例命令

Git log -n 5——5年前到2年前

的代码

from subprocess import check_output
from shlex import split

res = check_output(split('git log -n 5 --since "5 years ago" --until "2 year ago"'))
print(res)
>>> b'commit 7696ab087a163e084d6870bb4e5e4d4198bdc61a\nAuthor: Artur Barseghyan...'

如果没有shlex.split(),代码将如下所示

res = check_output([
    'git', 
    'log', 
    '-n', 
    '5', 
    '--since', 
    '5 years ago', 
    '--until', 
    '2 year ago'
])
print(res)
>>> b'commit 7696ab087a163e084d6870bb4e5e4d4198bdc61a\nAuthor: Artur Barseghyan...'