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diff --git a/man7/libc.7 b/man7/libc.7 new file mode 100644 index 0000000..7a62251 --- /dev/null +++ b/man7/libc.7 @@ -0,0 +1,115 @@ +.\" Copyright (c) 2009 Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH libc 7 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +libc \- overview of standard C libraries on Linux +.SH DESCRIPTION +The term \[lq]libc\[rq] is commonly used as a shorthand for +the \[lq]standard C library\[rq] +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 \[lq]libc\[rq] +to refer to the standard C library is somewhat ambiguous on Linux. +.SS glibc +By far the most widely used C library on Linux is the +.UR http://www.gnu.org\:/software\:/libc/ +GNU C Library +.UE , +often referred to as +.IR 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 +.I man-pages +project +(primarily in Section 3 of the manual). +Documentation of glibc is also available in the glibc manual, +available via the command +.IR "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. +.PP +The pathname +.I /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. +.SS Linux libc +In the early to mid 1990s, +there was for a while +.IR "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 \[lq]libc\[rq]. +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 +.IR libc.so.5 . +For a while, +Linux libc was the standard C library in many Linux distributions. +.PP +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 soname +.IR libc.so.6 . +.PP +Since the switch from Linux libc to glibc 2.0 occurred long ago, +.I 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 a few manual pages, +in particular, +references to +.I libc4 +and +.IR libc5 . +.SS 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 +.UR http://www\:.uclibc\:.org/ +.I uClibc +.UE , +.UR http://www\:.fefe\:.de/\:dietlibc/ +.I dietlibc +.UE , +and +.UR http://www\:.musl\-libc\:.org/ +.I "musl libc" +.UE . +Details of these libraries are covered by the +.I man-pages +project, +where they are known. +.SH SEE ALSO +.BR syscalls (2), +.BR getauxval (3), +.BR proc (5), +.BR feature_test_macros (7), +.BR man\-pages (7), +.BR standards (7), +.BR vdso (7) |