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<2)
{
printf("please print one param !\n");
return 0;
}
char buf[1024]={0};
char tmp[1024]={0};
sprintf(tmp,"df %s | sed -n '3p'|awk '{print $3}'",argv[1]);
FILE * file=popen(tmp,"r");
int count=0;
if(file!=NULL)
{
if(fgets(buf,1024,file)!=NULL)
{
long long freesize= strtoll(buf,NULL,10);
printf("size=%lld\n",freesize);
}
}
return 0;
}