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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 standard 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 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 com-
       mand 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 executing this pathname will cause glibc to display various information about the ver-
       sion 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 distribu-
       tions.  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 generally 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  informa-
       tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                             2009-01-13                           LIBC(7)