intro - introduction to library functions

       Section  3  of  the  manual  describes all library functions excluding the library functions (system call
       wrappers) described in Section 2, which implement system calls.

       Many of the functions described in the section are part of the Standard C Library (libc).  Some functions
       are part of other libraries (e.g., the math library, libm, or the real-time library, librt) in which case
       the manual page will indicate the linker option needed to link against the required  library  (e.g.,  -lm
       and -lrt, respectively, for the aforementioned libraries).

       In  some  cases,  the programmer must define a feature test macro in order to obtain the declaration of a
       function from the header file specified in the man page SYNOPSIS section.  (Where required, these featuretestmacros must be defined before including any header files.)  In such cases,  the  required  macro  is
       described in the man page.  For further information on feature test macros, see feature_test_macros(7).

   Subsections
       Section 3 of this manual is organized into subsections that reflect the complex structure of the standard
       C library and its many implementations:

       •  3const

       •  3head

       •  3type

       This  difficult  history  frequently  makes  it  a  poor example to follow in design, implementation, and
       presentation.

       Ideally, a library for the C language is designed such that each header file presents the interface to  a
       coherent  software  module.   It  provides  a small number of function declarations and exposes only data
       types and constants that are required for use of those functions.  Together, these are termed an  API  or
       applicationprograminterface.  Types and constants to be shared among multiple APIs should be placed in
       header files that declare no functions.  This organization permits a C library module  to  be  documented
       concisely  with  one  header  file  per  manual  page.   Such  an  approach  improves the readability and
       accessibility of library documentation, and thereby the usability of the software.

       intro - introduction to library functions

Authorsandcopyrightconditions
       Look at the header of the manual page source for the author(s) and copyright conditions.  Note that these
       can be different from page to page!

intro(2),   errno(3),   capabilities(7),  credentials(7),  environ(7),  feature_test_macros(7),  libc(7),
       math_error(7), path_resolution(7), pthreads(7), signal(7), standards(7), system_data_types(7)

Linux man-pages 6.9.1                              2024-05-02                                           intro(3)

       Certain terms and abbreviations are used to indicate UNIX variants and standards to which calls  in  this
       section conform.  See standards(7).