ece282/lab04/sample-getgrouplist.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

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

void main()
{
	gid_t  rgid, egid, sgid, *groups;
	struct group *grp;
	int num = 100, retval;
	
	if( getresgid(&rgid, &egid, &sgid) == -1 )
	{
		printf("Error\n");
		exit(1);
	}
	
	printf("%d %d %d\n", rgid, egid, sgid);

	if( (retval = getgrouplist( "hessamla", rgid, groups, &num)) <= num ){
		printf("Number of groups: %d\n", num);
		while ( retval--){
			printf("%d\n", groups[retval]);
		}
	}
	return;	
}