1 os.system
可以返回運行shell命令狀態，同時會在終端輸出運行結果
例如 ipython中運行如下命令，返回運行狀態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()
可以返回運行結果
popen(command [, mode='r' [, bufsize]]) -> pipeOpen a pipe to/from a command returning a file object.
運行返回結果
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 如何同時返回結果和運行狀態，commands模塊:
#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 使用模塊subprocess
ipython 中運行"?subprocess"可以發現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", retcodeexcept OSError, e: print >>sys.stderr, "Execution failed:", e
相對于上面幾種方式，subprocess便于控制和監控進程運行結果,subprocess提供多種函數便于應對父進程對子進程不同要求:
4.1.1 subprocess.call()
父進程父進程等待子進程完成，返回exit code
4.1.2 subprocess.check_call()
父進程等待子進程完成,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()
父進程等待子進程完成
返回子進程向標準輸出的輸出結果
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屬性為標準輸出的輸出結果，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
上面三個函數都是源于Popen()函數的wapper(封裝),如果需要更加個性化應用，那么就需要使用popen()函數
Popen對象創建后，主程序不會自動等待子進程完成。我們必須調用對象的wait()方法，父進程才會等待 (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 3999msparent process
參考文章:Python標準庫06 子進程 (subprocess包)
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