getgroups(2)                                                   getgroups(2)


   NAME
         getgroups, setgroups - get or set supplementary group access list IDs

   SYNOPSIS
         #include <unistd.h>

         int getgroups(int gidsetsize, gidt *grouplist)

         int setgroups(int ngroups, const gidt *grouplist)

   DESCRIPTION
         getgroups gets the current supplemental group access list of the
         calling process and stores the result in the array of group IDs
         specified by grouplist.  This array has gidsetsize entries and must
         be large enough to contain the entire list.  This list cannot be
         greater than {NGOUPSMAX}.  If gidsetsize equals 0, getgroups will
         return the number of groups to which the calling process belongs
         without modifying the array pointed to by grouplist.

         setgroups sets the supplementary group access list of the calling
         process from the array of group IDs specified by grouplist.  The
         number of entries is specified by ngroups and can not be greater than
         {NGROUPSMAX}.  This function may be invoked only by the super-user.

         getgroups will fail if:

         EINVAL         The value of gidsetsize is non-zero and less than the
                        number of supplementary group IDs set for the calling
                        process.

         setgroups will fail if:

         EINVAL         The value of ngroups is greater than {NGROUPSMAX}.

         EPERM          The effective user ID is not super-user.

         Either call will fail if:

         EFAULT         A referenced part of the array pointed to by grouplist
                        is outside of the allocated address space of the
                        process.

   SEE ALSO
         chown(2), getuid(2), setuid(2), initgroups(3C).
         groups(1) in the User's Reference Manual.

   DIAGNOSTICS
         Upon successful completion, getgroups returns the number of
         supplementary group IDs set for the calling process and setgroups
         returns the value 0.  Otherwise, a value of -1 is returned and errno
         is set to indicate the error.


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