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
我也遇到了同样的问题，但我想出了一个非常简单的方法:
import subprocess
output = subprocess.getoutput("ls -l")
print(output)
注意:此解决方案是特定于Python3的subprocess.getoutput()在Python2中不起作用
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 ""
对于相同的问题，我有一个稍微不同的需求:
捕获并返回STDOUT消息，因为它们在STDOUT缓冲区中累积(即实时)。 @vartec用python方法解决了这个问题，他使用生成器和“yield” 上面的字 打印所有STDOUT行(即使进程在STDOUT缓冲区可以完全读取之前退出) 不要浪费CPU周期以高频轮询进程 检查子流程的返回代码 如果得到非零错误返回码，则打印STDERR(与STDOUT分开)。
我综合了之前的答案，得出了以下结论:
import subprocess
from time import sleep
def run_command(command):
p = subprocess.Popen(command,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
shell=True)
# Read stdout from subprocess until the buffer is empty !
for line in iter(p.stdout.readline, b''):
if line: # Don't print blank lines
yield line
# This ensures the process has completed, AND sets the 'returncode' attr
while p.poll() is None:
sleep(.1) #Don't waste CPU-cycles
# Empty STDERR buffer
err = p.stderr.read()
if p.returncode != 0:
# The run_command() function is responsible for logging STDERR
print("Error: " + str(err))
这段代码的执行方式与前面的答案相同:
for line in run_command(cmd):
print(line)
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")
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
