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

我想建议你考虑一下simppl。它是一个可以通过pypi: pip install simppl获得的模块,运行在python3上。

Simppl允许用户运行shell命令并从屏幕上读取输出。

开发人员建议使用三种类型的用例:

最简单的用法是这样的: 从simppl。simple_pipeline导入simepipeline sp = SimplePipeline(start=0, end=100): sp.print_and_run(“< YOUR_FIRST_OS_COMMAND >”) sp.print_and_run(“< YOUR_SECOND_OS_COMMAND >”)' ' '


要同时运行多个命令,请使用: commands = ['<YOUR_FIRST_OS_COMMAND>', '<YOUR_SECOND_OS_COMMAND>'] Max_number_of_processes = 4 max_number_of_processes sp.run_parallel(命令)' ' '


最后,如果你的项目使用cli模块,你可以直接运行另一个command_line_tool作为管道的一部分。另一个工具会 从相同的进程中运行,但它将从日志中显示为 管道中的另一个命令。这使得调试和 重构调用其他工具的工具。 从example_module导入example_tool Sp.print_and_run_clt (example_tool.run, ['first_number', 'second_nmber'], {'-key1': 'val1', '-key2': 'val2'}, {“——国旗”})' ' '

请注意,打印到STDOUT/STDERR是通过python的日志模块。


下面是simppl工作原理的完整代码:

import logging
from logging.config import dictConfig

logging_config = dict(
    version = 1,
    formatters = {
        'f': {'format':
              '%(asctime)s %(name)-12s %(levelname)-8s %(message)s'}
        },
    handlers = {
        'h': {'class': 'logging.StreamHandler',
              'formatter': 'f',
              'level': logging.DEBUG}
        },
    root = {
        'handlers': ['h'],
        'level': logging.DEBUG,
        },
)
dictConfig(logging_config)

from simppl.simple_pipeline import SimplePipeline
sp = SimplePipeline(0, 100)
sp.print_and_run('ls')

其他回答

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

可以使用以下命令运行任何shell命令。我在ubuntu上使用过它们。

import os
os.popen('your command here').read()

注意:自python 2.6起已弃用。现在必须使用subprocess.Popen。下面是示例

import subprocess

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

例如,execute('ls -ahl') 区分三/四种可能的回报和操作系统平台:

没有输出,但运行成功 输出空行,运行成功 运行失败 输出一些东西,成功运行

下面的函数

def execute(cmd, output=True, DEBUG_MODE=False):
"""Executes a bash command.
(cmd, output=True)
output: whether print shell output to screen, only affects screen display, does not affect returned values
return: ...regardless of output=True/False...
        returns shell output as a list with each elment is a line of string (whitespace stripped both sides) from output
        could be 
        [], ie, len()=0 --> no output;    
        [''] --> output empty line;     
        None --> error occured, see below

        if error ocurs, returns None (ie, is None), print out the error message to screen
"""
if not DEBUG_MODE:
    print "Command: " + cmd

    # https://stackoverflow.com/a/40139101/2292993
    def _execute_cmd(cmd):
        if os.name == 'nt' or platform.system() == 'Windows':
            # set stdin, out, err all to PIPE to get results (other than None) after run the Popen() instance
            p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
        else:
            # Use bash; the default is sh
            p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True, executable="/bin/bash")

        # the Popen() instance starts running once instantiated (??)
        # additionally, communicate(), or poll() and wait process to terminate
        # communicate() accepts optional input as stdin to the pipe (requires setting stdin=subprocess.PIPE above), return out, err as tuple
        # if communicate(), the results are buffered in memory

        # Read stdout from subprocess until the buffer is empty !
        # if error occurs, the stdout is '', which means the below loop is essentially skipped
        # A prefix of 'b' or 'B' is ignored in Python 2; 
        # it indicates that the literal should become a bytes literal in Python 3 
        # (e.g. when code is automatically converted with 2to3).
        # return iter(p.stdout.readline, b'')
        for line in iter(p.stdout.readline, b''):
            # # Windows has \r\n, Unix has \n, Old mac has \r
            # if line not in ['','\n','\r','\r\n']: # Don't print blank lines
                yield line
        while p.poll() is None:                                                                                                                                        
            sleep(.1) #Don't waste CPU-cycles
        # Empty STDERR buffer
        err = p.stderr.read()
        if p.returncode != 0:
            # responsible for logging STDERR 
            print("Error: " + str(err))
            yield None

    out = []
    for line in _execute_cmd(cmd):
        # error did not occur earlier
        if line is not None:
            # trailing comma to avoid a newline (by print itself) being printed
            if output: print line,
            out.append(line.strip())
        else:
            # error occured earlier
            out = None
    return out
else:
    print "Simulation! The command is " + cmd
    print ""

根据@senderle的说法,如果你像我一样使用python3.6:

def sh(cmd, input=""):
    rst = subprocess.run(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, input=input.encode("utf-8"))
    assert rst.returncode == 0, rst.stderr.decode("utf-8")
    return rst.stdout.decode("utf-8")
sh("ls -a")

将完全像您在bash中运行命令一样

改进以获得更好的日志记录。 为了获得更好的输出,可以使用迭代器。 从下面开始,我们变得更好

from subprocess import Popen, getstatusoutput, PIPE
def shell_command(cmd):
    result = Popen(cmd, shell=True, stdout=PIPE, stderr=PIPE)

    output = iter(result.stdout.readline, b'')
    error = iter(result.stderr.readline, b'')
    print("##### OutPut ###")
    for line in output:
        print(line.decode("utf-8"))
    print("###### Error ########")
    for line in error:
        print(error.decode("utf-8")) # Convert bytes to str

    status, terminal_output = run_command(cmd)
    print(terminal_output)

shell_command("ls") # this will display all the files & folders in directory

使用getstatusoutput的其他方法(容易理解)

from subprocess import Popen, getstatusoutput, PIPE

status_Code, output = getstausoutput(command)
print(output) # this will give the terminal output

# status_code, output = getstatusoutput("ls") # this will print the all files & folder available in the directory