p5-16.c

来自「UNIX程序设计教程」· C语言 代码 · 共 31 行

#include <stdio.h>
#include <unistd.h>
#include <limits.h>
#include <grp.h>
main()
{
    int mem_grp, num_grp, i;
    int gidsetsize;
    gid_t *grouplist;
    struct group *groupinfo;
    char **ptr;
    /* 获得组成员个数并为附加组ID数组分配空间 */
    num_grp = getgroups(0,grouplist);  
    grouplist = (gid_t *)malloc((size_t)(sizeof(gid_t)*num_grp));
    /* 获得附加组ID */
    mem_grp = getgroups(num_grp, grouplist);
    printf("there are %d supplementary groups",mem_grp);
    /* 列出每个组的名字、组ID以及组成员名 */
    for (i=0; i<mem_grp; i++) {
        groupinfo = getgrgid(grouplist[i]);
        printf("\ngroup name is: %s \n", groupinfo->gr_name);
        printf("  group id is: %d\n", groupinfo->gr_gid); 
        printf("the members in this group are: ");  
        ptr = groupinfo->gr_mem;
        while ( *ptr ) {
            printf("%s, ", *ptr++);
        }
    }
        printf("\nDone\n");
}