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RedHat 9 (Linux i386) - man page for getpagesize (redhat section 2)

GETPAGESIZE(2)			    Linux Programmer's Manual			   GETPAGESIZE(2)

NAME
       getpagesize - get memory page size

SYNOPSIS
       #include <unistd.h>

       int getpagesize(void);

DESCRIPTION
       The  function  getpagesize()  returns the number of bytes in a page, where a "page" is the
       thing used where it says in the description of mmap(2) that files are mapped in page-sized
       units.

       The size of the kind of pages that mmap uses, is found using

	      #include <unistd.h>
	      long sz = sysconf(_SC_PAGESIZE);

       (where some systems also allow the synonym _SC_PAGE_SIZE for _SC_PAGESIZE), or

	      #include <unistd.h>
	      int sz = getpagesize();

HISTORY
       This call first appeared in 4.2BSD.

CONFORMING TO
       SVr4,  4.4BSD,  SUSv2.	In SUSv2 the getpagesize() call is labeled "legacy", and in POSIX
       1003.1-2001 it has been dropped.  HPUX does not have this call.

NOTES
       Whether getpagesize() is present as a Linux system call depends on the  architecture.   If
       it  is,	it  returns  the kernel symbol PAGE_SIZE, which is architecture and machine model
       dependent.  Generally, one uses binaries that  are  architecture  but  not  machine  model
       dependent, in order to have a single binary distribution per architecture. This means that
       a user program should not find PAGE_SIZE at compile time from a header file,  but  use  an
       actual  system  call,  at  least for those architectures (like sun4) where this dependency
       exists.	Here libc4, libc5, glibc 2.0 fail because their getpagesize()  returns	a  stati-
       cally derived value, and does not use a system call.  Things are OK in glibc 2.1.

SEE ALSO
       mmap(2), sysconf(3)

Linux 2.5.0				    2001-12-21				   GETPAGESIZE(2)


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