版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/wwwww_bw/article/details/53793157
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <fcntl.h>
#include <sys/stat.h>
int main()
{
struct sembuf sops;
{
struct sembuf sops;
int i;
int j;
int fd;
int j;
int fd;
int semit = semget(1234,1,IPC_CREAT);
if(-1 == semit)
{
printf("semget error\n");
}
{
printf("semget error\n");
}
i = semctl(semit,0,SETVAL,1);
if(-1 == i)
printf("semct error\n");
printf("semct error\n");
fd = open("sem",O_RDWR|O_CREAT|O_APPEND);
//while(1)
{
sops.sem_num = 0;
sops.sem_op = -1;
//while(1)
{
sops.sem_num = 0;
sops.sem_op = -1;
// fgets(buf,20,stdin);
write(fd,"hello world",12);
sleep(10);
write(fd,"hello world",12);
sleep(10);
sops.sem_num = 0;
sops.sem_op = +1;
sops.sem_op = +1;
semop(semit,&sops,1);
close(fd);
}
}
在不同终端上运行,下面一个尝试写的操作会等到上面写操作完成后执行,即两次写不会同时运行,
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <fcntl.h>
#include <sys/stat.h>
int main()
{
struct sembuf sops;
{
struct sembuf sops;
int i;
int j;
int fd;
// int *p;
int j;
int fd;
// int *p;
//p = (char*)malloc(sizeof(char));
int semit = semget(1234,1,IPC_CREAT);
if(-1 == semit)
{
printf("semget error\n");
}
{
printf("semget error\n");
}
i = semctl(semit,0,SETVAL,1);
if(-1 == i)
printf("semct error\n");
printf("semct error\n");
fd = open("sem",O_RDWR|O_CREAT|O_APPEND);
sops.sem_num = 0;
sops.sem_op = -1;
sops.sem_op = -1;
write(fd,"english",9);
sops.sem_num = 0;
sops.sem_op = +1;
sops.sem_op = +1;
semop(semit,&sops,1);
// printf("p = %s",p);
close(fd);
// printf("p = %s",p);
close(fd);
}