ngroups_max.5 (2010 09)

ngroups_max(5) ngroups_max(5)

(Tunable Kernel Parameters)

• Don’t associate users with more than 20 groups if they must run older applications.

• An individual user may require more than 20 groups, but have some applications which fail with more

than 20 groups.

One workaround is to start those applications with a wrapper program which truncates the list of sup-

plementary group IDs to the ﬁrst 20 groups and then invokes the application.

An example of such a wrapper program follows:

#include <limits.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

main (int argc, char **argv)

{

gid_t *list;

int ngroups;

int ret;

ngroups = getgroups(0, NULL);

if (ngroups > NGROUPS_MAX) {

list = (gid_t *)malloc(ngroups * sizeof(gid_t));

ngroups = getgroups(ngroups, list);

ret = setgroups(NGROUPS_MAX, list);

if (ret == -1) {

perror("setgroups");

exit(-1);

}

execvp(argv[1], &argv[1]);

perror("execvp");

exit(-1);

}

All HP-UX kernel tunable parameters are release speciﬁc. This parameter may be removed or have its

meaning changed in future releases of HP-UX.

Installation of optional kernel software, from HP or other vendors, may cause changes to tunable parame-

ter values. After installation, some tunable parameters may no longer be at the default or recommended

values. For information about the effects of installation on tunable values, consult the documentation for

the kernel software being installed. For information about optional kernel software that was factory

installed on your system, see HP-UX Release Notes at

http://www.hp.com/go/hpux-core-docs

AUTHOR

ngroups_max was developed by HP.