linux c文件锁flock

1.源码实现

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>

int main()
{
    FILE *fp = NULL;
    int i = 20;

    if((fp=fopen("./file.lock", "rb")) == NULL)
    {
        printf("file open error!\n");
        return -1;
    }

    /*给该文件加锁*/
    if(flock(fp->_fileno, LOCK_EX) != 0)
    {
        printf("file lock by others!\n");
        fclose(fp);
        return -1;
    }

    /*加锁时间为20s*/
    while(i)
    {
        printf("sleep %d\n", i--);
        sleep(1);
    }

    flock(fp->_fileno, LOCK_UN);

    fclose(fp);

    return 0;
}

2.编译源码

$ gcc -o file-1 file.c
$ gcc -o file-2 file.c

3.运行及其结果

$ ./file-1
$ ./file-2
sleep 20
sleep 19
sleep 18
sleep 17
sleep 16
sleep 15
sleep 14
sleep 13
sleep 12
sleep 11
sleep 10
sleep 9
sleep 8
sleep 7
sleep 6
sleep 5
sleep 4
sleep 3
sleep 2
sleep 1
sleep 20
sleep 19
sleep 18
sleep 17
sleep 16
sleep 15
sleep 14
sleep 13
sleep 12
sleep 11
sleep 10
sleep 9
sleep 8
sleep 7
sleep 6
sleep 5
sleep 4
sleep 3
sleep 2
sleep 1