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3.3. Library and Runtime Details

3.3.1. The GNU C Library

The glibc package contains the GNU C Library. This defines all functions specified by the ISO C standard, POSIX specific features, some Unix derivatives, and GNU-specific extensions. The most important set of shared libraries in the GNU C Library are the standard C and math libraries.
The GNU C Library defines its functions through specific header files, which you can declare in source code. Each header file contains definitions of a group of related facilities; for example, the stdio.h header file defines I/O-specific facilities, while math.h defines functions for computing mathematical operations.

3.3.1.1. GNU C Library Updates

The Red Hat Enterprise Linux 6 version of the GNU C Library features the following improvements over its Red Hat Enterprise Linux 5 version:
  • Added locales, including:
    • bo_CN
    • bo_IN
    • shs_CA
    • ber_DZ
    • ber_MA
    • en_NG
    • fil_PH
    • fur_IT
    • fy_DE
    • ha_NG
    • ig_NG
    • ik_CA
    • iu_CA
    • li_BE
    • li_NL
    • nds_DE
    • nds_NL
    • pap_AN
    • sc_IT
    • tk_TM
  • Added new interfaces, namely:
    • preadv
    • preadv64
    • pwritev
    • pwritev64
    • malloc_info
    • mkostemp
    • mkostemp64
  • Added new Linux-specific interfaces, namely:
    • epoll_pwait
    • sched_getcpu
    • accept4
    • fallocate
    • fallocate64
    • inotify_init1
    • dup3
    • epoll_create1
    • pipe2
    • signalfd
    • eventfd
    • eventfd_read
    • eventfd_write
  • Added new checking functions, namely:
    • asprintf
    • dprintf
    • obstack_printf
    • vasprintf
    • vdprintf
    • obstack_vprintf
    • fread
    • fread_unlocked
    • open*
    • mq_open
For a more detailed list of updates to the GNU C Library, refer to /usr/share/doc/glibc-version/NEWS . All changes as of version 2.6 apply to the GNU C Library in Red Hat Enterprise Linux 6. Some of these changes have also been backported to Red Hat Enterprise Linux 5 versions of glibc.

3.3.1.2. GNU C Library Documentation

The GNU C Library is fully documented in the GNU C Library manual; to access this manual locally, install glibc-devel and run info libc. An upstream version of this book is also available here:
http://www.gnu.org/software/libc/manual/html_mono/libc.html