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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 distribu-
       tions.  It is also the C library whose details are  documented  in  the
       relevant  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 sym-
       bolic 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 development
       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 features
       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 gener-
       ally 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 3.22 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)