使用 Python 子进程模块将输入传递给可执行文件 [英] Passing input to an executable using Python subprocess module

问题描述

我有一个名为 0.in 的输入文件.为了得到输出我做 ./a.out <0.in 在 Bash Shell 中.

I have an input file called 0.in. To get the output I do ./a.out < 0.in in the Bash Shell.

现在，我有几个这样的文件(超过 500 个)，我想使用 Python 的 subprocess 模块自动化这个过程.

Now, I have several such files (more than 500) and I want to automate this process using Python's subprocess module.

我试过这样做:

data=subprocess.Popen(['./a.out','< 0.in'],stdout=subprocess.PIPE,stdin=subprocess.PIPE).communicate()

当我运行此程序时，没有打印任何内容(数据 [0] 为空白).做我想做的事的正确方法是什么?

Nothing was printed (data[0] was blank) when I ran this. What is the right method to do what I want to do?

推荐答案

使用 < 进行重定向是 shell 功能，而不是 python 功能.

Redirection using < is a shell feature, not a python feature.

有两种选择:

1. 使用 shell=True 并让 shell 处理重定向:

1. Use shell=True and let the shell handle redirection:

data = subprocess.Popen(['./a.out < 0.in'], stdout=subprocess.PIPE, shell=True).communicate()

让python处理重定向:

Let python handle redirection:

with open('0.in') as f:
    data = subprocess.Popen(['./a.out'], stdout=subprocess.PIPE, stdin=f).communicate()

第二个选项通常是首选，因为它避免了 shell 的变幻莫测.

The second option is usually preferred because it avoids the vagaries of the shell.

如果要在data中捕获stderr，则将stderr=subprocess.PIPE添加到Popen命令中.否则，stderr 将出现在终端或发送 python 错误消息的任何地方.

If you want to capture stderr in data, then add stderr=subprocess.PIPE to the Popen command. Otherwise, stderr will appear on the terminal or wherever python's error messages are being sent.

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