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 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 (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. Since this switch occurred long 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
dietlibc
and
musl
libc Details of these libraries are covered by the
man-pages
project, where they are known.
SEE ALSO¶
syscalls(2),
getauxval(3),
proc(5),
feature_test_macros(7),
man-pages(7),
standards(7),
vdso(7)
COLOPHON¶
This page is part of release 3.74 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
http://www.kernel.org/doc/man-pages/.