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


     libc - overview of standard C libraries on Linux


     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.
     By  far  the  most  widely used C library on Linux is the GNU C Library
     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  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  begin-
     ning of 1997.
     The  pathname  /lib/ (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.  Linux libc4 was the last version to use the a.out
     binary format, and the first  version  to  provide  (primitive)  shared
     library support.  Linux libc 5 was the first version to support the ELF
     binary format; this version used the shared library  soname
     For  a  while, Linux libc was the standard C library in many Linux dis-
     However, notwithstanding the original motivations  of  the  Linux  libc
     effort,  by  the  time glibc 2.0 was released (in 1997), it was clearly
     superior to Linux libc, and all major Linux distributions that had been
     using  Linux  libc soon switched back to glibc.  To avoid any confusion
     with Linux libc versions, glibc 2.0 and later used the  shared  library
     Since  the  switch from Linux libc to glibc 2.0 occurred long ago, man-
     pages no longer takes care to document Linux libc  details.   Neverthe-
     less,  the  history  is  visible in vestiges of information about Linux
     libc that remain in a few 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 dietlibc and musl libc Details of these libraries
     are covered by the man-pages project, where they are known.


     syscalls(2),  getauxval(3),   proc(5),   feature_test_macros(7),   man-
     pages(7), standards(7), vdso(7)


     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at

Linux 2016-12-12 LIBC(7)

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