Question

我想知道unix命令组是否有任何备用C库，

$ groups ---- lists all the group id's of the user.

有一个名为getgroups（）的方法，但它返回用户此方法的组。有没有办法使用C为特定用户获取组。

Answer 1

#include "<grp.h>"
int getgrouplist(const char *user, gid_t group, gid_t *groups, int *ngroups);

Answer 2

这里是一个如何使用getgrouplist进行操作的示例，您可以随时提出任何问题。

__uid_t uid = getuid();//you can change this to be the uid that you want

struct passwd* pw = getpwuid(uid);
if(pw == NULL){
    perror("getpwuid error: ");
}

int ngroups = 0;

//this call is just to get the correct ngroups
getgrouplist(pw->pw_name, pw->pw_gid, NULL, &ngroups);
__gid_t groups[ngroups];

//here we actually get the groups
getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups);


//example to print the groups name
for (int i = 0; i < ngroups; i++){
    struct group* gr = getgrgid(groups[i]);
    if(gr == NULL){
        perror("getgrgid error: ");
    }
    printf("%s\n",gr->gr_name);
}

使用C在Linux中获取用户组的正确方法

2 个答案: