#include <grp.h>  #include <sys/types.h>

struct group * getgrent(void);

struct group
{
  char *gr_name; //组名称
  char *gr_passwd; //组密码
  gid_t gr_gid; //组识别码
  char **gr_mem; //组成员账号
}

#include <grp.h>
#include <sys/types.h>
main()
{
  struct group *data;
  int i;
  while((data = getgrent()) != 0)
  {
    i = 0;
    printf("%s:%s:%d:", data->gr_name, data->gr_passwd, data->gr_gid);
    while(data->gr_mem[i])
      printf("%s, ", data->gr_mem[i++]);
    printf("\n");
  }
  endgrent();
}

root:x:0:root,
bin:x:1:root, bin, daemon,
daemon:x:2:root, bin, daemon,
sys:x:3:root, bin, adm,
adm:x:4:root, adm, daemon
tty:x:5
disk:x:6:root
lp:x:7:daemon, lp
mem:x:8
kmem:x:9:
wheel:x:10:root
mail:x:12:mail
news:x:13:news
uucp:x:14:uucp
man:x:15:
games:x:20
gopher:x:30
dip:x:40
ftp:x:50
nobody:x:99

#include <grp.h>  #include <sys/types.h>

void setgrent(void);

getgrent, setgrent

#include <grp.h>  #include <sys/types.h>

void endgrent(void);