1 .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>
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23 .TH GETPAGESIZE 2 2010-09-20 "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)):
44 !(_POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600)
48 _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
49 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
56 returns the number of bytes in a page, where a "page" is the thing
57 used where it says in the description of
59 that files are mapped in page-sized units.
61 The size of the kind of pages that
68 long sz = sysconf(_SC_PAGESIZE);
72 (most systems allow the synonym
81 int sz = getpagesize();
85 .\" This call first appeared in 4.2BSD.
90 call is labeled LEGACY, and in POSIX.1-2001
92 HP-UX does not have this call.
93 Portable applications should employ
94 .I sysconf(_SC_PAGESIZE)
99 is present as a Linux system call depends on the architecture.
100 If it is, it returns the kernel symbol
102 whose value depends on the architecture and machine model.
103 Generally, one uses binaries that are dependent on the architecture but not
104 on the machine model, in order to have a single binary
105 distribution per architecture.
106 This means that a user program
109 at compile time from a header file,
110 but use an actual system call, at least for those architectures
111 (like sun4) where this dependency exists.
112 Here libc4, libc5, glibc 2.0 fail because their
114 returns a statically derived value, and does not use a system call.
115 Things are OK in glibc 2.1.