Linux 精确获取指定目录对应的块的剩余空间

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

int main(int argc,char *argv[])
{
    if(argc<)
    {
        printf("please print one param !\n");
        return ;
    }
    char buf[]={};
    char tmp[]={};
    sprintf(tmp,"df %s | sed -n '3p'|awk '{print $3}'",argv[]);
    FILE * file=popen(tmp,"r");
    int count=;
    if(file!=NULL)
    {
        if(fgets(buf,,file)!=NULL)
        {
            long long freesize= strtoll(buf,NULL,);
            printf("size=%lld\n",freesize);
        }
    }
    return ;
}