NAME

       getpagesize - get memory page size

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <unistd.h>

       int getpagesize(void);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getpagesize():
           Since glibc 2.20:
               _DEFAULT_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
           glibc 2.12 to glibc 2.19:
               _BSD_SOURCE || ! (_POSIX_C_SOURCE >= 200112L)
           Before glibc 2.12:
               _BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION

       The function getpagesize() returns the number of bytes in a memory page, where "page" is a
       fixed-length block, the unit for memory allocation and file mapping performed by mmap(2).

VERSIONS

       A user program should not hard-code a page size,  neither  as  a  literal  nor  using  the
       PAGE_SIZE macro, because some architectures support multiple page sizes.

       This manual page is in section 2 because Alpha, SPARC, and SPARC64 all have a Linux system
       call getpagesize() though other architectures do not, and use  the  ELF  auxiliary  vector
       instead.

STANDARDS

       None.

HISTORY

       This call first appeared in 4.2BSD.  SVr4, 4.4BSD, SUSv2.  In SUSv2 the getpagesize() call
       was labeled LEGACY, and it was removed in POSIX.1-2001.

       glibc 2.0 returned a constant even on architectures with multiple page sizes.

SEE ALSO

       mmap(2), sysconf(3)