December 2013
Intermediate to advanced
496 pages
8h 57m
Chinese
Content preview from LINUX系統程式設計 第二版
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
行程管理
|
167
舉例來說，假設你的程式想要取得特定子行程（pid 1742）的傳回值。但是，如果子行
程尚未終止，則立即返回。你可以使用如下的程式碼來完成此事：
int status;
pid_t pid;
pid = waitpid (1742, &status, WNOHANG);
if (pid ==
−
1)
perror ("waitpid");
else {
printf ("pid=%d\n", pid);
if (WIFEXITED (status))
printf ("Normal termination with exit status=%d\n",
WEXITSTATUS (status));
if (WIFSIGNALED (status))
printf ("Killed by signal=%d%s\n",
WTERMSIG (status),
WCOREDUMP (status) ? " (dumped core)" : "");
}
最後，請注意，如下的
wait()
用法：
wait (&status);
等效於如下的
waitpid()
用法：
waitpid (-1, &status, 0);
以更靈活的方式等待
在「等待子行程」功能上需要更大靈活度的應用程式，可以使用 POSIX 之 XSI 擴充所
定義（以及 Linux 所提供）的
waitid()
：
#include <sys/wait.h>
int waitid (idtype_t idtype,
id_t id,
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.