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  • wait

    1、wait阻塞父进程,没有子进程或SIGCHLD set to SIG_IGN 会失败,until status information for one of the terminated child processes of the calling process is available, or until delivery of a

    signal whose action is either to execute a signal-catching function or to terminate the process.

    2、status 什么时候是0:

    The process returned 0 from main().

    The process called _exit() or exit() with a status argument of 0.

    The process was terminated because the last thread in the process terminated.

    3、WIFEXITED(stat_val)

    Evaluates to a non-zero value if status was returned for a child process that terminated normally.  包括stat_val是0;但0是正常退出,其他exit(2)等退出。

    WEXITSTATUS (status); 只有stat_val== 0 才有意义。其他的比如signal的退出也都是0;

    4、WIFSIGNALED(stat_val)

    Evaluates to a non-zero value if status was returned for a child process that terminated due to the receipt of a signal that was not caught (see <signal.h>).

    WTERMSIG(stat_val)

    If the value of WIFSIGNALED(stat_val) is non-zero, this macro evaluates to the number of the signal that caused the termination of the child process.

    5、信号的status id号和exit的不同。

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  • 原文地址:https://www.cnblogs.com/wocgcow/p/5892914.html
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