GETGROUPS(2)              FreeBSD System Calls Manual             GETGROUPS(2)

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.

FreeBSD 13.1-RELEASE-p6        January 21, 2011        FreeBSD 13.1-RELEASE-p6