LIBC(7) 						     Linux Programmer's Manual							   LIBC(7)

NAME

       libc - Overview of standard C libraries on Linux

DESCRIPTION

       The  term  "libc"  is  commonly used as a shorthand for the "standard C library", a library of standard functions that can be used by all C
       programs (and sometimes by programs in other languages).  Because of some history (see below), use of the term "libc" to refer to the stan-
       dard C library is somewhat ambiguous on Linux.

   glibc
       By  far the most widely used C library on Linux is the GNU C Library (http://www.gnu.org/software/libc/), often referred to as glibc.  This
       is the C library that is nowadays used in all major Linux distributions.  It is also the C library whose details are documented in the rel-
       evant pages of the man-pages project (primarily in Section 3 of the manual).  Documentation of glibc is also available in the glibc manual,
       available via the command info libc.  Release 1.0 of glibc was made in September 1992.  (There were earlier 0.x releases.)  The next  major
       release of glibc was 2.0, at the beginning of 1997.

       The  pathname  /lib/libc.so.6 (or something similar) is normally a symbolic link that points to the location of the glibc library, and exe-
       cuting this pathname will cause glibc to display various information about the version installed on your system.

   Linux libc
       In the early to mid 1990s, there was for a while Linux libc, a fork of glibc 1.x created by Linux developers who felt that  glibc  develop-
       ment  at  the time was not sufficing for the needs of Linux.  Often, this library was referred to (ambiguously) as just "libc".	Linux libc
       released major versions 2, 3, 4, and 5 (as well as many minor versions of those releases).  For a while, Linux  libc  was  the  standard  C
       library in many Linux distributions.  However, notwithstanding the original motivations of the Linux libc effort, by the time glibc 2.0 was
       released, it was clearly superior to Linux libc, and all major Linux distributions that had been using Linux libc  soon	switched  back	to
       glibc.	(Since	this  switch occurred over a decade ago, man-pages no longer takes care to document Linux libc details.  Nevertheless, the
       history is visible in vestiges of information about Linux libc that remain in some manual pages, in particular,	references  to	libc4  and
       libc5.)

   Other C libraries
       There  are  various  other less widely used C libraries for Linux.  These libraries are generally smaller than glibc, both in terms of fea-
       tures and memory footprint, and often intended for building small binaries, perhaps targeted at development  for  embedded  Linux  systems.
       Among  such libraries are uClibc (http://www.uclibc.org/) and dietlibc (http://www.fefe.de/dietlibc/).  Details of these libraries are gen-
       erally not covered by the man-pages project.

SEE ALSO

       syscalls(2), feature_test_macros(7), man-pages(7), standards(7)

COLOPHON

       This page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2009-01-13								   LIBC(7)