trusty (7) libc.7.gz

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, 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.)

   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
       (http://www.uclibc.org/)  and  dietlibc  (http://www.fefe.de/dietlibc/).   Details of these libraries are
       generally not covered by the man-pages project.

SEE ALSO

       syscalls(2), feature_test_macros(7), man-pages(7), standards(7)

COLOPHON

       This page is part of release 3.54 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/.