stdin，stdout和stderr之间是否共享？(stdin, stdout and stderr are shared between?)

 我试图了解三个流的行为 - stdout ， stdin和stderr 。 我无法从任何教科书中得到答案，所以我来到这里。 
 
 我知道这三个存储在文件描述符表中，文件描述符为0（stdin），1（stdout）和2（stderr）。 我也知道这些不仅仅是文件描述符，而是可以重定向的I / O流。 好的，分享怎么样？ 
 
 考虑三种情况： 
 
 
 
 调用fork（）时 ：子进程和父进程共享文件描述符，但它们是否具有相同的stdin，stdout和stderr？ 
 
 
 创建线程时：线程共享文件描述符，但是I / O流？ 
 
 
 调用execl（）时 ：在这种情况下，当前过程映像将被新过程映像覆盖。 如果我执行execl("./a.out", "a.out", NULL); 那么这个新的可执行文件是否会获得stdin，stderr和stdout的全新副本？ 
 
 
 欢迎所有明智的答案。 

I am trying to understand the behavior of the three streams - stdout, stdin and stderr. I couldn't get the answer from any textbook, so I came here. 
 
I know that these three are stored in file descriptor table with file descriptors 0 (stdin), 1 (stdout) and 2 (stderr). I am also aware that these are not merely file descriptors but I/O streams which can be redirected. Ok, so how about sharing?
 
Consider the three cases:
 
 
 
When a fork() is called : The child process and parent process shares file descriptors, but do they have the same stdin, stdout and stderr ?
 
 
When a thread is created : Threads share file descriptors, but I/O streams?
 
 
When execl() is called : In this case the present process image is overwritten with new process image. If I do execl("./a.out", "a.out", NULL); , then will this new executable get a freshcopy of stdin, stderr and stdout?
 
 
All wise answers are welcome.

原文：https://stackoverflow.com/questions/26687602