linux文件函数

#include <stdio.h>
#include <fcntl.h>
#include <errno.h>

int main() {
    int fd = open("nonexistent_file.txt", O_RDONLY);
    if (fd == -1) {
        perror("Error opening file");
        // 检查errno以确定具体错误
        if (errno == ENOENT) {
            printf("File does not exist.\n");
        } else if (errno == EACCES) {
            printf("Permission denied.\n");
        } else if (errno == EBUSY) {
            printf("File is busy.\n");
        }
    } else {
        close(fd);
    }
    return 0;
}

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

int main() {
    int fd = open("example.txt", O_RDONLY);
    if (fd == -1) {
        perror("Error opening file");
        return 1;
    }

    char buffer[1024];
    off_t offset = 0;
    ssize_t bytesRead;

    while ((bytesRead = read(fd, buffer, sizeof(buffer))) > 0) {
        // 处理读取的数据
        printf("%.*s", (int)bytesRead, buffer);
        offset += bytesRead;
        lseek(fd, offset, SEEK_SET); // 重置文件指针位置
    }

    if (bytesRead == -1) {
        perror("Error reading file");
    }

    close(fd);
    return 0;
}