waitpid是如何来处理未决信号

Question

本人一直弄不清waitpid是怎么来处理未决信号的，主要是想知道waitpid(pid,&status,0)在处理未决信号时是一直等待还是有一个返回值？在些先谢谢了！

Answer 1

返回值存在 status中，至于阻塞的规则要看你 第三个参数的设置。

WNOHANG     return immediately if no child has exited.

WUNTRACED   also  return  if  a  child  has stopped (but not traced via
               ptrace(2)).  Status for traced children which have  stopped
               is provided even if this option is not specified.

WCONTINUED (since Linux 2.6.10)
                   also return if a stopped child has been resumed by delivery
                   of SIGCONT.

Answer 2

waitpid(pid,&status,0)我的第三个参数是0

Answer 3

高手去哪了…… 跪求呀……{:3_200:}