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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 14.0-RELEASE-p6 January 21, 2011 FreeBSD 14.0-RELEASE-p6