initgroups - initialize group access list
int initgroups(name, basegid)
const char *name;
Initgroups reads through the group file and sets up, using the
setgroups(2) call, the group access list for the user specified in
name. The basegid is automatically included in the groups list.
Typically this value is given as the group number from the password
Initgroups returns -1 if it was not invoked by the super-user.
Initgroups uses the routines based on getgrent(3). If the invoking
program uses any of these routines, the group structure will be
overwritten in the call to initgroups.