{ "content": [ { "type": "text", "text": "# libc (man)\n\n## NAME\n\nlibc - overview of standard C libraries on Linux\n\n## DESCRIPTION\n\nThe term “libc” is commonly used as a shorthand for the “standard C library” a library of\nstandard functions that can be used by all C programs (and sometimes by programs in other\nlanguages). Because of some history (see below), use of the term “libc” to refer to the\nstandard C library is somewhat ambiguous on Linux.\n\n## Sections\n\n- **NAME**\n- **DESCRIPTION** (3 subsections)\n- **SEE ALSO**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "libc", "section": "", "mode": "man", "summary": "libc - overview of standard C libraries on Linux", "synopsis": null, "tldr_summary": null, "tldr_examples": [], "tldr_source": null, "flags": [], "examples": [], "see_also": [ { "name": "syscalls", "section": "2", "url": "https://www.chedong.com/phpMan.php/man/syscalls/2/json" }, { "name": "getauxval", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/getauxval/3/json" }, { "name": "proc", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/proc/5/json" }, { "name": "featuretestmacros", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/featuretestmacros/7/json" }, { "name": "man-pages", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/man-pages/7/json" }, { "name": "standards", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/standards/7/json" }, { "name": "vdso", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/vdso/7/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "DESCRIPTION", "lines": 5, "subsections": [ { "name": "glibc", "lines": 12 }, { "name": "Linux libc", "lines": 19 }, { "name": "Other C libraries", "lines": 6 } ] }, { "name": "SEE ALSO", "lines": 4, "subsections": [] } ], "sections": { "NAME": { "content": "libc - overview of standard C libraries on Linux\n", "subsections": [] }, "DESCRIPTION": { "content": "The term “libc” is commonly used as a shorthand for the “standard C library” a library of\nstandard functions that can be used by all C programs (and sometimes by programs in other\nlanguages). Because of some history (see below), use of the term “libc” to refer to the\nstandard C library is somewhat ambiguous on Linux.\n", "subsections": [ { "name": "glibc", "content": "By far the most widely used C library on Linux is the \u001b]8;;http://www.gnu.org/software/libc/\u001b\\GNU C Library\u001b]8;;\u001b\\, often referred to as\nglibc. This is the C library that is nowadays used in all major Linux distributions. It is\nalso the C library whose details are documented in the relevant pages of the man-pages\nproject (primarily in Section 3 of the manual). Documentation of glibc is also available in\nthe glibc manual, available via the command info libc. Release 1.0 of glibc was made in Sep‐\ntember 1992. (There were earlier 0.x releases.) The next major release of glibc was 2.0, at\nthe beginning of 1997.\n\nThe pathname /lib/libc.so.6 (or something similar) is normally a symbolic link that points to\nthe location of the glibc library, and executing this pathname will cause glibc to display\nvarious information about the version installed on your system.\n" }, { "name": "Linux libc", "content": "In the early to mid 1990s, there was for a while Linux libc, a fork of glibc 1.x created by\nLinux developers who felt that glibc development at the time was not sufficing for the needs\nof Linux. Often, this library was referred to (ambiguously) as just “libc”. Linux libc re‐\nleased major versions 2, 3, 4, and 5, as well as many minor versions of those releases.\nLinux libc4 was the last version to use the a.out binary format, and the first version to\nprovide (primitive) shared library support. Linux libc 5 was the first version to support\nthe ELF binary format; this version used the shared library soname libc.so.5. For a while,\nLinux libc was the standard C library in many Linux distributions.\n\nHowever, notwithstanding the original motivations of the Linux libc effort, by the time glibc\n2.0 was released (in 1997), it was clearly superior to Linux libc, and all major Linux dis‐\ntributions that had been using Linux libc soon switched back to glibc. To avoid any confu‐\nsion with Linux libc versions, glibc 2.0 and later used the shared library soname libc.so.6.\n\nSince the switch from Linux libc to glibc 2.0 occurred long ago, man-pages no longer takes\ncare to document Linux libc details. Nevertheless, the history is visible in vestiges of in‐\nformation about Linux libc that remain in a few manual pages, in particular, references to\nlibc4 and libc5.\n" }, { "name": "Other C libraries", "content": "There are various other less widely used C libraries for Linux. These libraries are gener‐\nally smaller than glibc, both in terms of features and memory footprint, and often intended\nfor building small binaries, perhaps targeted at development for embedded Linux systems.\nAmong such libraries are \u001b]8;;http://www.uclibc.org/\u001b\\uClibc\u001b]8;;\u001b\\, \u001b]8;;http://www.fefe.de/dietlibc/\u001b\\dietlibc\u001b]8;;\u001b\\, and \u001b]8;;http://www.musl-libc.org/\u001b\\musl libc\u001b]8;;\u001b\\. Details of these libraries are\ncovered by the man-pages project, where they are known.\n" } ] }, "SEE ALSO": { "content": "syscalls(2), getauxval(3), proc(5), featuretestmacros(7), man-pages(7), standards(7),\nvdso(7)\n\nLinux man-pages 6.7 2023-10-31 libc(7)", "subsections": [] } } } }