如何通过python子进程与Mac上的应用程序进行交互? [英] How can I interact with an application on mac through python subprocess?

问题描述

我知道已经发布了类似的问题，但是我所见的任何方法似乎都不起作用.我想在Mac上使用python子进程启动应用程序xfoil，并使用脚本向xfoil发送一堆命令(xfoil是在终端窗口中运行的应用程序，您可以通过文本命令与之交互).我可以使用该脚本启动xfoil，但似乎无法找出如何向其发送命令.这是我目前正在尝试的代码:

import subprocess as sp

xfoil = sp.Popen(['open', '-a', '/Applications/Xfoil.app/Contents/MacOS/Xfoil'], stdin=sp.PIPE, stdout=sp.PIPE)

stdout_data = xfoil.communicate(input='NACA 0012')

我也尝试过

xfoil.stdin.write('NACA 0012\n')

以便将命令发送到xfoil.

解决方案

作为 xfoil.wait() (或其他方法)隐式地wait s)以防止这种情况发生.

I know there are similar questions posted already, but non of the methods I have seen seems to work. I want to launch the application xfoil, on mac, with python subprocess, and send xfoil a bunch of commands with a script (xfoil is an application that runs in a terminal window and you interact with it through text commands). I am able to launch xfoil with the script, but I can't seem to find out how to send commands to it. This is the code I am currently trying:

import subprocess as sp

xfoil = sp.Popen(['open', '-a', '/Applications/Xfoil.app/Contents/MacOS/Xfoil'], stdin=sp.PIPE, stdout=sp.PIPE)

stdout_data = xfoil.communicate(input='NACA 0012')

I have also tried

xfoil.stdin.write('NACA 0012\n')

in order to send commands to xfoil.

解决方案

As the man page says,

The open command opens a file (or a directory or URL), just as if you had double-clicked the file's icon.

Ultimately, the application gets started by LaunchServices, but that's not important—what's important is that it's not a child of your shell, or Python script.

Also, the whole point of open is to open the app itself, so you don't have to dig into it and find the Unix executable file. If you already have that, and want to run it as a Unix executable… just run it:

xfoil = sp.Popen(['/Applications/Xfoil.app/Contents/MacOS/Xfoil'], stdin=sp.PIPE, stdout=sp.PIPE)

As it turns out, in this case, MacOS/Xfoil isn't even the right program; it's apparently some kind of wrapper around Resources/xfoil, which is the actual equivalent to what you get as /usr/local/bin/xfoil on linux. So you want to do this:

xfoil = sp.Popen(['/Applications/Xfoil.app/Contents/Resouces/xfoil'], stdin=sp.PIPE, stdout=sp.PIPE)

(Also, technically, your command line shouldn't even work at all; the -a specifies an application, not a Unix executable, and you're supposed to pass at least one file to open. But because LaunchServices can launch Unix executables as if they were applications, and open doesn't check that the arguments are valid, open -a /Applications/Xfoil.app/Contents/MacOS/Xfoil ends up doing effectively the same thing as open /Applications/Xfoil.app/Contents/MacOS/Xfoil.)

---

For the benefit of future readers, I'll include this information from the comments:

If you just write a line to stdin and then return from the function/fall off the end of the main script/etc., the Popen object will get garbage collected, closing both of its pipes. If xfoil hasn't finished running yet, it will get an error the next time it tries to write any output, and apparently it handles this by printing Fortran runtime error: end of file (to stderr?) and bailing. You need to call xfoil.wait() (or something else that implicitly waits) to prevent this from happening.

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