SETGROUPS(2)                                                      SETGROUPS(2)


NAME
     setgroups - set group access list

SYNOPSIS
     #include <sys/param.h>

   POSIX:
     int setgroups(int ngroups, gid_t *gidset);
   BSD:
     int setgroups(int ngroups, int *gidset);

     To use the BSD version of setgroups, one must either

     1) explicitly invoke it as BSDsetgroups or

     2) link with the libbsd.a library:

          cc -o prog prog.c -lbsd


DESCRIPTION
     setgroups initializes the group access list of the current user process
     according to the array gidset.  The parameter ngroups indicates the
     number of entries in the array.  The sysconf(_SC_NGROUPS_MAX) system call
     may be used to determine at runtime the maximum allowable value for
     ngroups in the particular kernel configuration (it is an lbootable value
     (ngroups_max) which is declared in /var/sysgen/master.d/kernel).  If
     using the BSD version, ngroups may never be greater than NGROUPS (as
     defined in <sys/param.h>).

     Setting ngroups_max to zero and rebooting effectively disables multiple-
     groups system-wide.  In most cases, however, it will be set to a value
     between NGROUPS_UMIN and NGROUPS_UMAX (also defined in <sys/param.h>).

     Only the super-user may set new groups or alter the value of ngroups_max.

RETURN VALUE
     A successful call returns the number of groups in the group set.  A value
     of -1 indicates that an error occurred, and the error code is stored in
     the global variable errno.

ERRORS
     The setgroups call will fail if:

     [EPERM]        The caller is not the super-user.

     [EFAULT]       The address specified for gidset is outside the process
                    address space.

     [EINVAL]       The ngroups parameter is greater than NGROUPS or the
                    kernel maximum, as specified above.


SEE ALSO
     multgrps(1), getgroups(2), initgroups(3), sysconf(2)

CAVEATS
     The POSIX and 4.3BSD versions differ in the types of their gidset
     parameter.


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