在子进程中使用管道

Question

我想将一个命令的输出传递给另一个命令。 必须在命令1执行完成之后运行命令2，依此类推。 我尝试使用'subprocess.Popen（）'的'wait'。 但是它不起作用。

有人可以帮我吗？

使用的代码：

proc= subprocess.Popen(['python27','scriptA.py',file],cwd="C:\pythonPrograms\\",stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
proc.wait()
sortedop= subprocess.Popen(['sort'],cwd="C:\pythonPrograms\\",stdout=subprocess.PIPE,stdin=proc.stdout, stderr=subprocess.STDOUT)
sortedop.wait()
countReducer= subprocess.Popen(['python27', 'scriptB.py'],cwd="C:\pythonPrograms\\",stdout=subprocess.PIPE,stdin=sortedop.stdout, stderr=subprocess.STDOUT)
countReducer.wait()
fd = open(file+".json", 'w')
countpostprocesser= subprocess.Popen(['python27', 'scriptC.py'],cwd="C:\pythonPrograms\\",stdout=fd,stdin=countReducer.stdout,stderr=subprocess.STDOUT,shell=True)
countpostprocesser.wait()
fd.close()

Answer 1

如果您确实希望一个脚本在下一个脚本开始之前完成，并且输出数据不是太大，则可以将数据读入内存：

proc= subprocess.Popen(['python27','scriptA.py',file],cwd="C:\\pythonPrograms\\",stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate()
sortedop= subprocess.Popen(['sort'],cwd="C:\pythonPrograms\\",stdout=subprocess.PIPE,stdin=subprocess.PIPE, stderr=subprocess.STDOUT)
out, err = sortedop.communicate(out)
countReducer= subprocess.Popen(['python27', 'scriptB.py'],cwd="C:\pythonPrograms\\",stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.STDOUT)
out, err = countReducer.communicate(out)
fd = open(file+".json", 'w')
countpostprocesser= subprocess.Popen(['python27', 'scriptC.py'],cwd="C:\pythonPrograms\\",stdout=fd, stderr=subprocess.STDOUT)
out, err = countpostprocesser.communicate(out)