使用c++检查Linux系统硬盘空间，如果空间少于200m时删除最老的文件

使用C语言检查Linux系统硬盘空间，如果空间少于200MB，删除最早的文件可以使用下面的代码：

#include <sys/statvfs.h>
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <string.h>
#include <unistd.h>
#include <time.h>

#define THRESHOLD 200*1024*1024 // 200MB in bytes

int main(int argc, char* argv[])
{
    struct statvfs disk_stat;
    if (statvfs("/", &disk_stat) != 0)
    {
        perror("statvfs");
        return 1;
    }

    unsigned long long free_space = disk_stat.f_frsize * disk_stat.f_bfree;
    if (free_space < THRESHOLD)
    {
        DIR *dir = opendir("/");
        if (dir == NULL)
        {
            perror("opendir");
            return 1;
        }

        struct dirent *entry = readdir(dir);
        while (entry != NULL)
        {
            if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
            {
                entry = readdir(dir);
                continue;
            }

            char path[1024];
            snprintf(path, sizeof(path), "/%s", entry->d_name);

            struct stat file_stat;
            if (lstat(path, &file_stat) != 0)
            {
                perror("lstat");
                return 1;
            }

            if (S_ISREG(file_stat.st_mode))
            {
                time_t oldest_time = time(NULL);
                char oldest_file[1024];

                struct dirent *inner_entry = readdir(dir);
                while (inner_entry != NULL)
                {
                    char inner_path[1024];
                    snprintf(inner_path, sizeof(inner_path), "/%s", inner_entry->d_name);

                    struct stat inner_file_stat;
                    if (lstat(inner_path, &inner_file_stat) != 0)
                    {
                        perror("lstat");
                        return 1;
                    }

                    if (S_ISREG(inner_file_stat.st_mode) && inner_file_stat.st_mtime < oldest_time)
                    {
                        oldest_time = inner_file_stat.st_mtime;
                        strncpy(oldest_file, inner_path, sizeof(oldest_file));
                    }

                    inner_entry = readdir(dir);
                }

                if (remove(oldest_file) != 0)
                {
                    perror("remove");
                    return 1;
                }

                if (statvfs("/", &