chmod更改文件的权限

 #include "apue.h"

 int main(int argc,char *argv[])
 {
     struct stat stabuf;

     if(stat("zbzhuang",&stabuf) < )
         err_sys("stat error for foo");
     if(chmod("zbzhuang",(stabuf.st_mode & ~S_IXGRP)|S_ISGID) < )
         err_sys("chmod error for foo");

     if(chmod("caylin",S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < )
         err_sys("chmod error for bar");

     return ;
 }