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Historically autofs mounts were not included in mount table listings. This is the case in other SysV autofs implementations and was also the case with Linux autofs. But now that /etc/mtab is a symlink to the proc filesystem mount table the autofs mount entries appear in the mount table on Linux. Prior to the symlinking of /etc/mtab mount table it was sufficient to call mount(2) and simply not update /etc/mtab to exclude autofs mounts from mount listings. Also, with the symlinking of /etc/mtab we have seen a shift in usage toward using the proc mount tables directly. But the autofs mount entries need to be retained when coming from the proc file system for applications that need them (largely autofs file system users themselves) so filtering out these entries within the kernel itself can't be done. So it needs be done in user space. There are three reasons to omit the autofs mount entries. One is that certain types of auto-mounts have an autofs mount for every entry in their autofs mount map and these maps can be quite large. This leads to mount table listings containing a lot of unnecessary entries. Also, this change in behaviour between autofs implementations can cause problems for applications that use getmntent(3) in other OS implementations as well as Linux. Lastly, there's very little that user space can do with autofs mount entries since this must be left to the autofs mount owner, typically the automount daemon. But it can also lead to attempts to access automount managed paths resulting mounts being triggered when they aren't needed or mounts staying mounted for much longer thay they need be. While the point of this change ins't to help with these problems (and it can be quite a problem) it may be a welcome side effect. So the Linux autofs file system has been modified to accept a pseudo mount option of "ignore" (as is used in other OS implementations) so that user space can use this as a hint to skip autofs entries on reading the mount table. The Linux autofs automount daemon used getmntent(3) itself and has been modified to use the proc file system directly so that it can "ignore" mount option. The use of this mount option is opt-in and a configuration option has been added which defaults to not use this option so if there are applications that need these entries, other than autofs itself, they can be retained. Also, since this filtering is based on an added mount option earlier versions of Linux autofs iand other autofs file system users will not use the option and so won't be affected by the change.
This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 ia64-*-linux-gnu m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see http://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at http://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see http://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.