NAME | DESCRIPTION | SEE ALSO | COLOPHON

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

NAME         top

       libc - overview of standard C libraries on Linux

DESCRIPTION         top

       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 dis‐
       tributions.  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 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 stan‐
       dard 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, refer‐
       ences 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/⟩ dietlibc
       ⟨http://www.fefe.de/dietlibc/⟩, and musl libc ⟨http://www.musl-
       libc.org/⟩.  Details of these libraries are generally not covered by
       the man-pages project.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 3.65 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                            2014-04-20                          LIBC(7)