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

            
#String form: 
            
              
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)對父進(jìn)程對子進(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，則舉出錯誤subprocess.CalledProcessError，該對象包含有returncode屬性，可用try...except...來檢查

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，則舉出錯誤subprocess.CalledProcessError，該對象包含有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

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

Popen對象創(chuàng)建后，主程序不會自動等待子進(jìn)程完成。我們必須調(diào)用對象的wait()方法，父進(jìn)程才會等待 (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
          

以上內(nèi)容就是本文的全部敘述，希望大家喜歡。