| NAME | DESCRIPTION | SEE ALSO | COLOPHON | The Linux Programming Interface |
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 standard C library is somewhat
ambiguous on Linux.
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 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.
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.)
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.
syscalls(2), feature_test_macros(7), man-pages(7), standards(7)
This page is part of release 3.32 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)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface