linux 文件操作系统函数

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

int main() {
    FILE *file = fopen("nonexistent_file.txt", "r");
    if (file == NULL) {
        printf("Failed to open file: %s\n", strerror(errno));
        return 1;
    }
    fclose(file);
    return 0;
}

#include <stdio.h>

int main() {
    FILE *file = fopen("example.txt", "r+");
    if (file == NULL) {
        perror("Failed to open file");
        return 1;
    }

    char buffer[1024];
    size_t bytesRead = fread(buffer, 1, sizeof(buffer), file);
    if (bytesRead == 0 && ferror(file)) {
        perror("Failed to read file");
        fclose(file);
        return 1;
    }

    // 处理读取的数据...

    if (fwrite(buffer, 1, bytesRead, file) != bytesRead) {
        perror("Failed to write file");
        fclose(file);
        return 1;
    }

    fclose(file);
    return 0;
}

#include <stdio.h>
#include <sys/stat.h>

int main() {
    if (chmod("example.txt", S_IRUSR | S_IWUSR) == -1) {
        perror("Failed to change file permissions");
        return 1;
    }
    return 0;
}