#include <stdio.h>

 #include <string.h>

 #include <errno.h>

 static long get_used_space(const char *dir) {

     long lUsedSpace = ;

     char cmd[] = "";

     char buf[] = "";

     snprintf(cmd, , "du -sk %s | awk '{print $1}'", dir);

     printf("%s\n", cmd);

     FILE *pFile = popen(cmd, "r");

     if (pFile == NULL) {

         printf("popen() failed, error:%s\n", strerror(errno));

         return lUsedSpace;

     }

     fgets(buf, sizeof(buf), pFile);

     pclose(pFile);

     lUsedSpace = atol(buf);

     return lUsedSpace;

 }

 int main()

 {

     long lUsedSpace = get_used_space("/var/log/");

     printf("UsedSpace:%ld\n", lUsedSpace);

     return ;

 }