1 .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
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23 .TH GETPAGESIZE 2 2007-07-26 "Linux" "Linux Programmer's Manual"
25 getpagesize \- get memory page size
27 .B #include <unistd.h>
29 .B int getpagesize(void);
32 Feature Test Macro Requirements for glibc (see
33 .BR feature_test_macros (7)):
37 _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
41 returns the number of bytes in a page, where a "page" is the thing
42 used where it says in the description of
44 that files are mapped in page-sized units.
46 The size of the kind of pages that
53 long sz = sysconf(_SC_PAGESIZE);
57 (most systems allow the synonym
66 int sz = getpagesize();
70 .\" This call first appeared in 4.2BSD.
75 call is labeled LEGACY, and in POSIX.1-2001
77 HP-UX does not have this call.
78 Portable applications should employ
79 .I sysconf(_SC_PAGESIZE)
84 is present as a Linux system call depends on the architecture.
85 If it is, it returns the kernel symbol
87 whose value depends on the architecture and machine model.
88 Generally, one uses binaries that are dependent on the architecture but not
89 on the machine model, in order to have a single binary
90 distribution per architecture.
91 This means that a user program
94 at compile time from a header file,
95 but use an actual system call, at least for those architectures
96 (like sun4) where this dependency exists.
97 Here libc4, libc5, glibc 2.0 fail because their
99 returns a statically derived value, and does not use a system call.
100 Things are OK in glibc 2.1.