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).  Doc-
       umentation 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 executing 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 develop-
       ment  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 3.25 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)