1LIBC(7) Linux Programmer's Manual LIBC(7)
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6 libc - Overview of standard C libraries on Linux
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9 The term "libc" is commonly used as a shorthand for the "standard C
10 library", a library of standard functions that can be used by all C
11 programs (and sometimes by programs in other languages). Because of
12 some history (see below), use of the term "libc" to refer to the stan‐
13 dard C library is somewhat ambiguous on Linux.
14 glibc
16 By far the most widely used C library on Linux is the GNU C Library
17 (http://www.gnu.org/software/libc/), often referred to as glibc. This
18 is the C library that is nowadays used in all major Linux distribu‐
19 tions. It is also the C library whose details are documented in the
20 relevant pages of the man-pages project (primarily in Section 3 of the
21 manual). Documentation of glibc is also available in the glibc manual,
22 available via the command info libc. Release 1.0 of glibc was made in
23 September 1992. (There were earlier 0.x releases.) The next major
24 release of glibc was 2.0, at the beginning of 1997.
25 The pathname /lib/libc.so.6 (or something similar) is normally a sym‐
27 bolic link that points to the location of the glibc library, and exe‐
28 cuting this pathname will cause glibc to display various information
29 about the version installed on your system.
30 Linux libc
32 In the early to mid 1990s, there was for a while Linux libc, a fork of
33 glibc 1.x created by Linux developers who felt that glibc development
34 at the time was not sufficing for the needs of Linux. Often, this
35 library was referred to (ambiguously) as just "libc". Linux libc
36 released major versions 2, 3, 4, and 5 (as well as many minor versions
37 of those releases). For a while, Linux libc was the standard C library
38 in many Linux distributions. However, notwithstanding the original
39 motivations of the Linux libc effort, by the time glibc 2.0 was
40 released, it was clearly superior to Linux libc, and all major Linux
41 distributions that had been using Linux libc soon switched back to
42 glibc. (Since this switch occurred over a decade ago, man-pages no
43 longer takes care to document Linux libc details. Nevertheless, the
44 history is visible in vestiges of information about Linux libc that
45 remain in some manual pages, in particular, references to libc4 and
46 libc5.)
47 Other C libraries
49 There are various other less widely used C libraries for Linux. These
50 libraries are generally smaller than glibc, both in terms of features
51 and memory footprint, and often intended for building small binaries,
52 perhaps targeted at development for embedded Linux systems. Among such
53 libraries are uClibc (http://www.uclibc.org/) and dietlibc
54 (http://www.fefe.de/dietlibc/). Details of these libraries are gener‐
55 ally not covered by the man-pages project.
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58 syscalls(2), feature_test_macros(7), man-pages(7), standards(7)
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61 This page is part of release 3.25 of the Linux man-pages project. A
62 description of the project, and information about reporting bugs, can
63 be found at http://www.kernel.org/doc/man-pages/.
64Linux 2009-01-13 LIBC(7)