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python在2.4版本后引入subprocess来管理子进程，简单来说就是可以调用外部程序，取代之前os.system,os.spawn等旧的的方法其中subprocess提供了多种方法来执行子进程，分别是subprocess.callsubprocess.check_allsubprocess.check_outputsubprocess.Popen>>> retcode=subprocess.call(["ls","-al"])total 1865448drwxr-xr-x  30 tiantao User       4096  2月 12 20:22 .drwxr-xr-x 204 root    root       4096  1月 14 14:10 ..-rw-r--r--   1 tiantao User     234911  1月  2 18:59 afterdrwx------   4 tiantao User       4096  9月 15  2017 .ansible-rw-------   1 tiantao User          0  3月  2  2018 .ansible_galaxy>>> print retcode0>>>上面语句可以看到和直接执行ls -al的结果是一样的，直接输出ls -al的执行结果，并且ls -al结果为零，类似于shell中的$?例如原本在shell中的语句output=`mycmd myarg`# becomesoutput = check_output(["mycmd", "myarg"])output=`dmesg | grep hda` # becomesoutput=check_output("dmesg | grep hda", shell=True)status = os.system("mycmd" + " myarg")# becomesstatus = subprocess.call("mycmd" + " myarg", shell=True)或者这个来判断命令执行后的返回值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 as e:    print >>sys.stderr, "Execution failed:", e使用Popen可以替代os.spwalppid = os.spawnlp(os.P_NOWAIT, "/bin/mycmd", "mycmd", "myarg")==>pid = Popen(["/bin/mycmd", "myarg"]).pidos.spawnvp(os.P_NOWAIT, path, args)==>Popen([path] + args[1:])

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