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日常整理python執(zhí)行系統(tǒng)命令的常見(jiàn)方法(全)

更新時(shí)間：2015年10月22日 16:39:28 投稿：mrr

本文是小編日常整理的些關(guān)于python執(zhí)行系統(tǒng)命令常見(jiàn)的方法，比較全面，特此通過(guò)腳本之家這個(gè)平臺(tái)把此篇文章分享給大家供大家參考

具體內(nèi)容如下：

1 os.system

例如 ipython中運(yùn)行如下命令，返回運(yùn)行狀態(tài)status

os.system('cat /etc/passwdqc.conf')
min=disabled,24,11,8,7
max=40
passphrase=3
match=4
similar=deny
random=47
enforce=everyone
retry=3
Out[6]: 0

2 os.popen()

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

運(yùn)行返回結(jié)果

In [20]: output = os.popen('cat /proc/cpuinfo')
In [21]: lineLen = []
In [22]: for line in output.readlines():
    lineLen.append(len(line))
   ....:
In [23]: line
line     lineLen
In [23]: lineLen
Out[23]:
[14,
25,
...

3 如何同時(shí)返回結(jié)果和運(yùn)行狀態(tài)，commands模塊:

#String form: <module 'commands' from '/usr/lib64/python2.7/commands.pyc'>
File: /usr/lib64/python2.7/commands.py
Docstring:
Execute shell commands via os.popen() and return status, output.
Interface summary:
import commands
outtext = commands.getoutput(cmd)
(exitstatus, outtext) = commands.getstatusoutput(cmd)
outtext = commands.getstatus(file) # returns output of "ls -ld file"
A trailing newline is removed from the output string.
Encapsulates the basic operation:
pipe = os.popen('{ ' + cmd + '; } 2>&1', 'r')
text = pipe.read()
sts = pipe.close()

commands示例如下:

In [24]: (status, output) = commands.getstatusoutput('cat /proc/cpuinfo')
In [25]: status
Out[25]: 0
In [26]: len(output)
Out[26]: 3859

4 使用模塊subprocess

ipython 中運(yùn)行"?subprocess"可以發(fā)現(xiàn)subprocess是python用來(lái)替換os.popen()等管道操作命令的新模塊

A more real-world example would look like this:

try:
 retcode = call("mycmd" + " myarg", shell=True)
 if retcode < 0:
  print >>sys.stderr, "Child was terminated by signal", -retcode
 else:
  print >>sys.stderr, "Child returned", retcode
except OSError, e:
 print >>sys.stderr, "Execution failed:", e

相對(duì)于上面幾種方式，subprocess便于控制和監(jiān)控進(jìn)程運(yùn)行結(jié)果,subprocess提供多種函數(shù)便于應(yīng)對(duì)父進(jìn)程對(duì)子進(jìn)程不同要求:

4.1.1 subprocess.call()

父進(jìn)程父進(jìn)程等待子進(jìn)程完成，返回exit code

4.1.2 subprocess.check_call()

父進(jìn)程等待子進(jìn)程完成,返回0，如果returncode不為0，則舉出錯(cuò)誤subprocess.CalledProcessError，該對(duì)象包含有returncode屬性，可用try...except...來(lái)檢查

4.1.3 subprocess.check_output()

父進(jìn)程等待子進(jìn)程完成

返回子進(jìn)程向標(biāo)準(zhǔn)輸出的輸出結(jié)果

檢查退出信息，如果returncode不為0，則舉出錯(cuò)誤subprocess.CalledProcessError，該對(duì)象包含有returncode屬性和output屬性，output屬性為標(biāo)準(zhǔn)輸出的輸出結(jié)果，可用try...except...來(lái)檢查

例如:

In [32]: out = subprocess.call("ls -l", shell=True)
total 42244
-rw-rw-r--. 1 *** *** 366 May 26 09:10 ChangeLog

4.2.1

上面三個(gè)函數(shù)都是源于Popen()函數(shù)的wapper(封裝),如果需要更加個(gè)性化應(yīng)用，那么就需要使用popen()函數(shù)

Popen對(duì)象創(chuàng)建后，主程序不會(huì)自動(dòng)等待子進(jìn)程完成。我們必須調(diào)用對(duì)象的wait()方法，父進(jìn)程才會(huì)等待 (也就是阻塞block)

[wenwt@localhost syntax]$ rm subprocess.pyc 
[wenwt@localhost syntax]$ python process.py 
parent process
[wenwt@localhost syntax]$ PING www.google.com (173.194.219.99) 56(84) bytes of data.
^C
[wenwt@localhost syntax]$ 
--- www.google.com ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 3999ms

加上wait方法:

[wenwt@localhost syntax]$ python process.py 
PING www.google.com (173.194.219.103) 56(84) bytes of data.
--- www.google.com ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 3999ms
parent process

補(bǔ)充介紹：Python 執(zhí)行終端命令的方法

import os
import subprocess
'''
os.system模塊
os.system("ls -hl") 執(zhí)行命令并返回狀態(tài)碼，當(dāng)返回0表示成功；返回256表示失敗，痛點(diǎn)是無(wú)法返回output
os.popen模塊
os.popen("ls -hl") 執(zhí)行命令，之后通過(guò).read()方法獲取output返回值
subprocess模塊
subprocess.getstatusoutput("ls -hl") 執(zhí)行命令，并返回狀態(tài)status、輸出output
subprocess.getoutput("ls -hl")    執(zhí)行命令，只返回輸出結(jié)果output
subprocess.call("ls -hl")      執(zhí)行命令并返回狀態(tài)碼 和os.system("ls -hl")類似
'''
def test_system(cmd):
  status = os.system(cmd) # 會(huì)自動(dòng)輸出output到控制臺(tái) 但是無(wú)法接收，status為0表示成功、status為256表示失敗
  print(status)
def test_popen(cmd):
  output = os.popen(cmd).read() # 只會(huì)獲取到命令的output，如果是有output的錯(cuò)誤命令 會(huì)輸出output，否則輸出空白
  print(output)
def test_getoutput(cmd):
  output = subprocess.getoutput(cmd) # 和os.popen(cmd)類似
  print(output)
def test_getstatusoutput(cmd):
  status, output = subprocess.getstatusoutput(cmd) # 執(zhí)行命令，并返回狀態(tài)status、輸出output
  print(status)
  print(output)
def test_call(cmd):
  status = subprocess.call(cmd) # 和os.system(cmd)類似
  print(status)
if __name__ == '__main__':
  # test_system('ls -lh') # test_system('test')
  # test_popen('pwd') # test_popen('test')
  # test_getoutput('pwd')
  # test_getstatusoutput('pwd')
  test_call('pwd')

以上內(nèi)容就是本文的全部敘述，希望大家喜歡。

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