linux c文件操作函数

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

int main() {
    int fd = open("example.txt", O_RDONLY);
    if (fd == -1) {
        perror("Error opening file");
        exit(EXIT_FAILURE);
    }
    close(fd);
    return 0;
}

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

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

    char buffer[1024];
    ssize_t bytesRead = read(fd, buffer, sizeof(buffer) - 1);
    if (bytesRead == -1) {
        perror("Error reading file");
        close(fd);
        exit(EXIT_FAILURE);
    }

    buffer[bytesRead] = '\0';
    printf("%s\n", buffer);

    close(fd);
    return 0;
}

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

int main() {
    int fd = open("example.txt", O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd == -1) {
        perror("Error opening file");
        exit(EXIT_FAILURE);
    }

    const char *data = "Hello, World!";
    ssize_t bytesWritten = write(fd, data, strlen(data));
    if (bytesWritten == -1) {
        perror("Error writing to file");
        close(fd);
        exit(EXIT_FAILURE);
    }

    fsync(fd); // Ensure data is written to disk
    close(fd);
    return 0;
}