转 Python执行系统命令的方法

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Python执行系统命令的方法

http://www.linux-field.com/?p=15

Python中执行系统命令常见方法有两种：

两者均需 import os

(1) os.system

# 仅仅在一个子终端运行系统命令，而不能获取命令执行后的返回信息

system(command) -> exit_status
Execute the command (a string) in a subshell.

# 如果再命令行下执行，结果直接打印出来

 >>> os.system('ls')
 04101419778.CHM   bash      document    media      py-django   video
 11.wmv            books     downloads   Pictures  python
 all-20061022      Desktop   Examples    project    tools

(2) os.popen

# 该方法不但执行命令还返回执行后的信息对象

popen(command [, mode='r' [, bufsize]]) -> pipe
Open a pipe to/from a command returning a file object.

例如：

 >>>tmp = os.popen('ls *.py').readlines()
 >>>tmp
 Out[21]:
 ['dump_db_pickle.py ',
 'dump_db_pickle_recs.py ',
 'dump_db_shelve.py ',
 'initdata.py ',
 '__init__.py ',
 'make_db_pickle.py ',
 'make_db_pickle_recs.py ',
 'make_db_shelve.py ',
 'peopleinteract_query.py ',
 'reader.py ',
 'testargv.py ',
 'teststreams.py ',
 'update_db_pickle.py ',
 'writer.py ']

好处在于：将返回的结果赋于一变量，便于程序的处理。

(3)  使用模块subprocess

 >>> import subprocess
 >>> subprocess.call (["cmd", "arg1", "arg2"],shell=True)

获取返回和输出:

 import subprocess
 p = subprocess.Popen('ls', shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
 for line in p.stdout.readlines():
     print line,
 retval = p.wait()

(4)  使用模块commands模块

 >>> import commands
 >>> dir(commands)
 ['__all__', '__builtins__', '__doc__', '__file__', '__name__', 'getoutput', 'getstatus','getstatusoutput', 'mk2arg', 'mkarg']
 >>> commands.getoutput("date")
 'Wed Jun 10 19:39:57 CST 2009'
 >>>
 >>> commands.getstatusoutput("date")
 (0, 'Wed Jun 10 19:40:41 CST 2009')

注意： 当执行命令的参数或者返回中包含了中文文字，那么建议使用subprocess，如果使用os.popen则会出现下面的错误:

 Traceback (most recent call last):
   File "./test1.py", line 56, in <module>
     main()
   File "./test1.py", line 45, in main
     fax.sendFax()
   File "./mailfax/Fax.py", line 13, in sendFax
     os.popen(cmd)
 UnicodeEncodeError: 'ascii' codec can't encode characters in position 46-52: ordinal not inrange(128)

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标签: Python, commands, subprocess, popen