NAME

       setgroups — set group access list

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <sys/param.h>
       #include <unistd.h>

       int
       setgroups(int ngroups, const gid_t *gidset);

DESCRIPTION

       The setgroups() system call sets the group access list of the current user process according to the array
       gidset.   The  ngroups  argument  indicates  the  number of entries in the array and must be no more than
       {NGROUPS_MAX}+1.

       Only the super-user may set a new group list.

       The first entry of the group array (gidset[0]) is used as the effective group-ID for the  process.   This
       entry  is  over-written  when  a  setgid program is run.  To avoid losing access to the privileges of the
       gidset[0] entry, it should be duplicated later in the group array.  By convention, this  happens  because
       the  group  value  indicated  in  the  password  file also appears in /etc/group.  The group value in the
       password file is placed in gidset[0] and that value then gets added a second  time  when  the  /etc/group
       file is scanned to create the group set.

RETURN VALUES

       The  setgroups()  function  returns the value 0 if successful; otherwise the value -1 is returned and the
       global variable errno is set to indicate the error.

ERRORS

       The setgroups() system call will fail if:

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

       [EINVAL]           The number specified in the ngroups argument is larger than the {NGROUPS_MAX}+1 limit.

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

SEE ALSO

       getgroups(2), initgroups(3)

HISTORY

       The setgroups() system call appeared in 4.2BSD.

Debian                                          January 19, 2018                                    SETGROUPS(2)