golden hour

/usr/include/bits

File/Folder	Size	Actions
a.out.h	268 B
byteswap-16.h	1.69 KB
byteswap.h	5.56 KB
cmathcalls.h	4.7 KB
confname.h	23.19 KB
dirent.h	1.69 KB
dlfcn.h	2.47 KB
elfclass.h	426 B
endian.h	176 B
environments.h	3.5 KB
epoll.h	1.11 KB
errno.h	2.11 KB
error.h	2.62 KB
eventfd.h	1.1 KB
fcntl-linux.h	12.55 KB
fcntl.h	2.19 KB
fcntl2.h	5.44 KB
fenv.h	3.94 KB
fenvinline.h	190 B
huge_val.h	1.83 KB
huge_valf.h	1.79 KB
huge_vall.h	1.57 KB
hwcap.h	966 B
in.h	9.01 KB
inf.h	1.03 KB
initspin.h	25 B
inotify.h	1.05 KB
ioctl-types.h	2.41 KB
ioctls.h	4.38 KB
ipc.h	2.01 KB
ipctypes.h	1.14 KB
libc-lock.h	12.54 KB
libio-ldbl.h	1014 B
link.h	4.2 KB
local_lim.h	3.13 KB
locale.h	1.33 KB
math-finite.h	14.24 KB
mathcalls.h	11.3 KB
mathdef.h	2.14 KB
mathinline.h	30.86 KB
mman.h	4.78 KB
monetary-ldbl.h	1.02 KB
mqueue.h	1.22 KB
mqueue2.h	2.11 KB
msq.h	2.47 KB
nan.h	1.54 KB
netdb.h	1.25 KB
param.h	1.4 KB
poll.h	2.04 KB
poll2.h	2.86 KB
posix1_lim.h	4.81 KB
posix2_lim.h	2.82 KB
posix_opt.h	5.65 KB
printf-ldbl.h	986 B
pthreadtypes.h	6.33 KB
resource.h	9.21 KB
sched.h	7.37 KB
select.h	2.08 KB
select2.h	1.4 KB
sem.h	2.53 KB
semaphore.h	1.21 KB
setjmp.h	1.26 KB
setjmp2.h	1.67 KB
shm.h	3.44 KB
sigaction.h	2.79 KB
sigcontext.h	4.08 KB
siginfo.h	9.81 KB
signalfd.h	1.04 KB
signum.h	3.34 KB
sigset.h	4.48 KB
sigstack.h	1.49 KB
sigthread.h	1.64 KB
sockaddr.h	1.5 KB
socket.h	12.6 KB
socket2.h	2.95 KB
socket_type.h	2.16 KB
stab.def	8.82 KB
stat.h	7.46 KB
statfs.h	1.89 KB
statvfs.h	3.34 KB
stdio-ldbl.h	3.11 KB
stdio-lock.h	2.14 KB
stdio.h	5.45 KB
stdio2.h	12.36 KB
stdio_lim.h	1.34 KB
stdlib-float.h	1.12 KB
stdlib-ldbl.h	1.36 KB
stdlib.h	5.53 KB
string.h	56.48 KB
string2.h	46.08 KB
string3.h	4.38 KB
sys_errlist.h	1.19 KB
syscall.h	43.03 KB
sysctl.h	893 B
syslog-ldbl.h	1.17 KB
syslog-path.h	1.03 KB
syslog.h	1.66 KB
termios.h	5.23 KB
time.h	3.35 KB
timerfd.h	1.08 KB
timex.h	4.36 KB
types.h	7.55 KB
typesizes.h	3.15 KB
uio.h	2.42 KB
unistd.h	13.07 KB
ustat.h	1.06 KB
utmp.h	3.87 KB
utmpx.h	3.38 KB
utsname.h	1.19 KB
waitflags.h	1.61 KB
waitstatus.h	3.49 KB
wchar-ldbl.h	2.45 KB
wchar.h	1.11 KB
wchar2.h	20.04 KB
wordsize.h	327 B
xopen_lim.h	3.68 KB

Edit: posix_opt.h

/* Define POSIX options for Linux.
   Copyright (C) 1996-2004, 2006, 2008, 2009 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of the
   License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If
   not, see <http://www.gnu.org/licenses/>.  */

#ifndef	_BITS_POSIX_OPT_H
#define	_BITS_POSIX_OPT_H	1

/* Job control is supported.  */
#define	_POSIX_JOB_CONTROL	1

/* Processes have a saved set-user-ID and a saved set-group-ID.  */
#define	_POSIX_SAVED_IDS	1

/* Priority scheduling is supported.  */
#define	_POSIX_PRIORITY_SCHEDULING	200809L

/* Synchronizing file data is supported.  */
#define	_POSIX_SYNCHRONIZED_IO	200809L

/* The fsync function is present.  */
#define	_POSIX_FSYNC	200809L

/* Mapping of files to memory is supported.  */
#define	_POSIX_MAPPED_FILES	200809L

/* Locking of all memory is supported.  */
#define	_POSIX_MEMLOCK	200809L

/* Locking of ranges of memory is supported.  */
#define	_POSIX_MEMLOCK_RANGE	200809L

/* Setting of memory protections is supported.  */
#define	_POSIX_MEMORY_PROTECTION	200809L

/* Some filesystems allow all users to change file ownership.  */
#define	_POSIX_CHOWN_RESTRICTED	0

/* `c_cc' member of 'struct termios' structure can be disabled by
   using the value _POSIX_VDISABLE.  */
#define	_POSIX_VDISABLE	'\0'

/* Filenames are not silently truncated.  */
#define	_POSIX_NO_TRUNC	1

/* X/Open realtime support is available.  */
#define _XOPEN_REALTIME	1

/* X/Open thread realtime support is available.  */
#define _XOPEN_REALTIME_THREADS	1

/* XPG4.2 shared memory is supported.  */
#define	_XOPEN_SHM	1

/* Tell we have POSIX threads.  */
#define _POSIX_THREADS	200809L

/* We have the reentrant functions described in POSIX.  */
#define _POSIX_REENTRANT_FUNCTIONS      1
#define _POSIX_THREAD_SAFE_FUNCTIONS	200809L

/* We provide priority scheduling for threads.  */
#define _POSIX_THREAD_PRIORITY_SCHEDULING	200809L

/* We support user-defined stack sizes.  */
#define _POSIX_THREAD_ATTR_STACKSIZE	200809L

/* We support user-defined stacks.  */
#define _POSIX_THREAD_ATTR_STACKADDR	200809L

/* We support priority inheritence.  */
#define _POSIX_THREAD_PRIO_INHERIT	200809L

/* We support priority protection, though only for non-robust
   mutexes.  */
#define _POSIX_THREAD_PRIO_PROTECT	200809L

#ifdef __USE_XOPEN2K8
/* We support priority inheritence for robust mutexes.  */
# define _POSIX_THREAD_ROBUST_PRIO_INHERIT	200809L

/* We do not support priority protection for robust mutexes.  */
# define _POSIX_THREAD_ROBUST_PRIO_PROTECT	-1
#endif

/* We support POSIX.1b semaphores.  */
#define _POSIX_SEMAPHORES	200809L

/* Real-time signals are supported.  */
#define _POSIX_REALTIME_SIGNALS	200809L

/* We support asynchronous I/O.  */
#define _POSIX_ASYNCHRONOUS_IO	200809L
#define _POSIX_ASYNC_IO		1
/* Alternative name for Unix98.  */
#define _LFS_ASYNCHRONOUS_IO	1
/* Support for prioritization is also available.  */
#define _POSIX_PRIORITIZED_IO	200809L

/* The LFS support in asynchronous I/O is also available.  */
#define _LFS64_ASYNCHRONOUS_IO	1

/* The rest of the LFS is also available.  */
#define _LFS_LARGEFILE		1
#define _LFS64_LARGEFILE	1
#define _LFS64_STDIO		1

/* POSIX shared memory objects are implemented.  */
#define _POSIX_SHARED_MEMORY_OBJECTS	200809L

/* CPU-time clocks support needs to be checked at runtime.  */
#define _POSIX_CPUTIME	0

/* Clock support in threads must be also checked at runtime.  */
#define _POSIX_THREAD_CPUTIME	0

/* GNU libc provides regular expression handling.  */
#define _POSIX_REGEXP	1

/* Reader/Writer locks are available.  */
#define _POSIX_READER_WRITER_LOCKS	200809L

/* We have a POSIX shell.  */
#define _POSIX_SHELL	1

/* We support the Timeouts option.  */
#define _POSIX_TIMEOUTS	200809L

/* We support spinlocks.  */
#define _POSIX_SPIN_LOCKS	200809L

/* The `spawn' function family is supported.  */
#define _POSIX_SPAWN	200809L

/* We have POSIX timers.  */
#define _POSIX_TIMERS	200809L

/* The barrier functions are available.  */
#define _POSIX_BARRIERS	200809L

/* POSIX message queues are available.  */
#define	_POSIX_MESSAGE_PASSING	200809L

/* Thread process-shared synchronization is supported.  */
#define _POSIX_THREAD_PROCESS_SHARED	200809L

/* The monotonic clock might be available.  */
#define _POSIX_MONOTONIC_CLOCK	0

/* The clock selection interfaces are available.  */
#define _POSIX_CLOCK_SELECTION	200809L

/* Advisory information interfaces are available.  */
#define _POSIX_ADVISORY_INFO	200809L

/* IPv6 support is available.  */
#define _POSIX_IPV6	200809L

/* Raw socket support is available.  */
#define _POSIX_RAW_SOCKETS	200809L

/* We have at least one terminal.  */
#define _POSIX2_CHAR_TERM	200809L

/* Neither process nor thread sporadic server interfaces is available.  */
#define _POSIX_SPORADIC_SERVER	-1
#define _POSIX_THREAD_SPORADIC_SERVER	-1

/* trace.h is not available.  */
#define _POSIX_TRACE	-1
#define _POSIX_TRACE_EVENT_FILTER	-1
#define _POSIX_TRACE_INHERIT	-1
#define _POSIX_TRACE_LOG	-1

/* Typed memory objects are not available.  */
#define _POSIX_TYPED_MEMORY_OBJECTS	-1

/* Streams are not available.  */
#define _XOPEN_STREAMS	-1

#endif /* bits/posix_opt.h */