NAME

       getgroups — get group access list

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       int
       getgroups(int gidsetlen, gid_t *gidset);

DESCRIPTION

       The  getgroups()  system call gets the current group access list of the user process and stores it in the
       array gidset.  The gidsetlen argument indicates the number of entries that may be placed in gidset.   The
       getgroups() system call returns the actual number of groups returned in gidset.  At least one and as many
       as  {NGROUPS_MAX}+1  values  may  be  returned.   If gidsetlen is zero, getgroups() returns the number of
       supplementary group IDs associated with the calling process without modifying the  array  pointed  to  by
       gidset.

       The  value  of  {NGROUPS_MAX}  should  be  obtained  using  sysconf(3)  to  avoid hard-coding it into the
       executable.

RETURN VALUES

       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 possible errors for getgroups() are:

       [EINVAL]           The argument gidsetlen is smaller than the number of groups in the group set.

       [EFAULT]           The argument gidset specifies an invalid address.

SEE ALSO

       setgroups(2), initgroups(3), sysconf(3)

STANDARDS

       The getgroups() system call conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

HISTORY

       The getgroups() system call appeared in 4.2BSD.

Debian                                          January 21, 2011                                    GETGROUPS(2)