Python os.popen：如何确保popen（...）在继续之前完成执行？

Question

我有以下代码：

pwd = '/home/user/svnexport/Repo/'

updateSVN = "svn up " + pwd
cmd = os.popen(updateSVN)

getAllInfo = "svn info " + pwd + "branches/* " + pwd + "tags/* " + pwd + "trunk/*"
cmd = os.popen(getAllInfo)

在cmd = os.popen(updateSVN)开始执行之前，我如何确定cmd = os.popen(getAllInfo)已完成执行？

Answer 1

您应该使用subprocess：

import subprocess
import glob
pwd = '/home/user/svnexport/Repo/'

updateSVN = ["svn", "up", pwd]
cmd = subprocess.Popen(updateSVN)
status = cmd.wait()

# the same can be achieved in a shorter way:
filelists = [glob.glob(pwd + i + "/*") for i in ('branches', 'tags', 'trunk')]
filelist = sum(filelists, []) # add them together

getAllInfo = ["svn", "info"] + filelist
status = subprocess.call(getAllInfo)

如果您需要捕获子流程的输出，请执行

process = subprocess.Popen(..., stdout=subprocess.PIPE)
data = process.stdout.read()
status = subprocess.wait()

Answer 2

如果您需要终止第一个命令，则不需要多线程。你可以做到

os.system(updateSVN)
os.system(getAllInfo)

如果您真的想使用updateSVN，可以通过

等待它

for _ in cmd:
    pass

Answer 3

尝试使用wait（）方法：

pwd = '/home/user/svnexport/Repo/'

updateSVN = "svn up " + pwd
cmd = os.popen(updateSVN)
cmd.wait()

getAllInfo = "svn info " + pwd + "branches/* " + pwd + "tags/* " + pwd + "trunk/*"
cmd = os.popen(getAllInfo)

Answer 4

如果您想等待，最简单的方法是使用以下子进程函数之一

• 致电
• check_call
• check_output

只有在shell中的命令执行完成后，才会返回其中的每一个，请参阅docs for details