python执行系统命令

来源:转载

1 os.system

例如 ipython中运行如下命令,返回运行状态status

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

 

2 os.popen()

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

运行返回结果

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

 

3 如何同时返回结果和运行状态,commands模块:

#String form: <module 'commands' from '/usr/lib64/python2.7/commands.pyc'>File: /usr/lib64/python2.7/commands.pyDocstring:Execute shell commands via os.popen() and return status, output.Interface summary:import commandsouttext = 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]: statusOut[25]: 0In [26]: len(output)Out[26]: 3859

 

4 使用模块subprocess

ipython 中运行"?subprocess"可以发现subprocess是python用来替换os.popen()等管道操作命令的新模块

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", retcodeexcept OSError, e: print >>sys.stderr, "Execution failed:", e

相对于上面几种方式,subprocess便于控制和监控进程运行结果,subprocess提供多种函数便于应对父进程对子进程不同要求:

4.1.1 subprocess.call()

父进程父进程等待子进程完成,返回exit code

4.1.2 subprocess.check_call()

父进程等待子进程完成,返回0,如果returncode不为0,则举出错误subprocess.CalledProcessError,该对象包含有returncode属性,可用try...except...来检查

4.1.3 subprocess.check_output()

父进程等待子进程完成

返回子进程向标准输出的输出结果

检查退出信息,如果returncode不为0,则举出错误subprocess.CalledProcessError,该对象包含有returncode属性和output属性,output属性为标准输出的输出结果,可用try...except...来检查

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 

上面三个函数都是源于Popen()函数的wapper(封装),如果需要更加个性化应用,那么就需要使用popen()函数

Popen对象创建后,主程序不会自动等待子进程完成。我们必须调用对象的wait()方法,父进程才会等待 (也就是阻塞block)

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

加上wait方法:

[[email protected] 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 3999msparent process

 

参考文章:Python标准库06 子进程 (subprocess包)

 


分享给朋友:
您可能感兴趣的文章:
随机阅读: