问题描述
我正在从 Python 运行一个 C 可执行文件,这个可执行文件有时会出现段错误.当它发生段错误时,子进程模块不会在 stdout 或 stderr 中返回任何内容.
I'm running a C executable from Python and this executable sometimes segfaults. When it segfaults the subprocess module does not return anything in stdout or stderr.
示例代码:
import subprocess proc = subprocess.Popen(['./a.out'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE) out, err = proc.communicate() print 'out: "%s"' % out print 'err: "%s"' % err print proc.returncode
a.out的来源是:
int main() { printf("hello world "); int x = 1 / 0; }
./a.out的输出是:
hello world Floating point exception
Python 代码的输出是(在 Linux 中,python 2.7):
The output of the Python code is (in Linux, python 2.7):
out: "" err: "" -8
有没有办法在可执行文件崩溃的情况下获取它的输出?
Is there a way to get the output of the executable even if it crashes?
将返回码转换为字符串消息的通用方法也不错.
A generic method to translate returncode to a string message, would also be nice.
推荐答案
你的 C 程序没有刷新它的输出缓冲区.解决此问题的最简单方法是将 STDOUT 的输出模式更改为无缓冲:
Your C program is not flushing its output buffer. The easiest way around this problem is to change the output mode of STDOUT to unbuffered:
#include <stdio.h> int main(int argc,char **argv) { setvbuf(stdout,_IONBF,0,0); printf("hello world "); int x = 1 / 0; }
现在您的程序(我对其进行了编辑以修复错字)产生了正确的输出:
Now your program (which I edited to fix a typo) produces the correct output:
$ python2.7 x.py out: "hello world " err: "" 0 $
在我的 Mac 上返回码是 0,令人困惑,因为因信号而终止的程序没有返回码.
The return code is 0 on my Mac, confusingly, because programs that are terminated for a signal don't have a return code.