linux wait£¨£©²»Ìî²ÎÊý µÈ´ý×ÓÏß³Ì

#include <semaphore.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>

void print(pid_t pid);
sem_t *sem;/*¶¨ÒåposixÓÐÃûÐźŵÆ*/
int val;/*¶¨ÒåÐźŵƵ±Ç°Öµ*/

int main(int argc,char *argv[])
{
int n=0;

if(argc!=2)
{
printf("please input a sem name!\n");
exit(1);
}

sem=sem_open(argv[1],O_CREAT,0644,2);/*´ò¿ªÒ»¸öÐźŵƣ¬³õÖµÉèΪ2*/
while(n++ <5)/*Ñ­»·´´½¨5¸ö×Ó½ø³Ì£¬Ê¹ËûÃÇͬ²½ÔËÐÐ*/
{
if(fork()==0)
{
sem_wait(sem);/*ÉêÇëÐźŵÆ*/
print(getpid());/*µ÷Óù²Ïí´úÂë¶Î*/
sleep(1);
sem_post(sem);/*ÊÍ·ÅÐźŵÆ*/
printf("I'm finished,my pid is %d\n",getpid());
exit(0);//return 0;
}
}

wait();/*µÈ´ýËùÓÐ×Ó½ø³Ì½áÊø*/-----ÕâÀïwait¿ÉÒÔ²»Ìî²ÎÊýµÈ´ýËùÓÐ×Ó½ø³ÌÂð£¿
//while(wait(NULL)!= -1)
// ;
sem_close(sem);
sem_unlink(argv[1]);
        printf("---reach here---\n");
exit(0);
}

void print(pid_t pid)
{
printf("I get it,my pid is %d\n",pid);
sem_getvalue(sem,&val);
printf("Now the semvalue is %d\n",val);
}

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[ken@localhost 3]$ ./sem_in_mprocess test        &