getpwnam

#include <stdio.h>
#include <pwd.h>
int main()
{
        struct passwd * pw;
        char *username = "apple";
        pw = getpwnam(username);
        if (!pw) {
                printf("%s is not exist\n", username);
                return -1;
        }
        printf("pw->pw_name = %s\n", pw->pw_name);
        printf("pw->pw_passwd = %s\n", pw->pw_passwd);
        printf("pw->pw_uid = %d\n", pw->pw_uid);
        printf("pw->pw_gid = %d\n", pw->pw_gid);
        printf("pw->pw_gecos = %s\n", pw->pw_gecos);
        printf("pw->pw_dir = %s\n", pw->pw_dir);
        printf("pw->pw_shell = %s\n", pw->pw_shell);
}