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GETGROUPS(2)                BSD System Calls Manual               GETGROUPS(2)

NAME
     getgroups -- get group access list

SYNOPSIS
     #include <unistd.h>

     int
     getgroups(int gidsetsize, gid_t grouplist[]);

DESCRIPTION
     Getgroups() gets the current group access list of the current user process and stores it in the array
     grouplist[].  The parameter gidsetsize indicates the number of entries that may be placed in
     grouplist[].  Getgroups() returns the actual number of groups returned in grouplist[].  No more than
     {NGROUPS_MAX} will ever be returned.  If gidsetsize is 0, getgroups() returns the number of groups
     without modifying the grouplist[] array.

RETURN VALUES
     A successful call returns the number of groups in the group set.  Otherwise, a value of -1 is returned
     and the global integer variable errno is set to indicate the error.

ERRORS
     The possible errors for getgroups() are:

     [EFAULT]           The argument grouplist specifies an invalid address.

     [EINVAL]           The argument gidsetsize, although non-zero, is smaller than the number of groups in
                        the group set.

LEGACY SYNOPSIS
     #include <sys/param.h>
     #include <sys/types.h>
     #include <unistd.h>

     The include files <sys/param.h> and <sys/types.h> are necessary.

SEE ALSO
     setgroups(2), initgroups(3), compat(5)

HISTORY
     The getgroups() function call appeared in 4.2BSD.

4.2 Berkeley Distribution       April 16, 1994       4.2 Berkeley Distribution