1 .\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
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25 .TH LSEEK64 3 2013-08-19 "Linux" "Linux Programmer's Manual"
27 lseek64 \- reposition 64-bit read/write file offset
29 .BR "#define _LARGEFILE64_SOURCE" " /* See feature_test_macros(7) */"
31 .B #include <sys/types.h>
33 .B #include <unistd.h>
35 .BI "off64_t lseek64(int " fd ", off64_t " offset ", int " whence );
39 family of functions reposition the offset of the open file associated
40 with the file descriptor
44 bytes relative to the start, current position, or end of the file,
54 For more details, return value, and errors, see
57 Four interfaces are available:
61 and the raw system call
68 .BI "off_t lseek(int " fd ", off_t " offset ", int " whence );
75 This is a 32-bit signed type on 32-bit architectures, unless one
80 #define _FILE_OFFSET_BITS 64
84 in which case it is a 64-bit signed type.
90 .BI "off64_t lseek64(int " fd ", off64_t " offset ", int " whence );
96 uses a 64-bit type even when
99 Its prototype (and the type
101 is available only when one compiles with
105 #define _LARGEFILE64_SOURCE
111 .\" in glibc 2.0.94, not in 2.0.6
112 is available since glibc 2.1, and is defined to be an alias for
119 .BI "loff_t llseek(int " fd ", loff_t " offset ", int " whence );
125 is a 64-bit signed type.
128 .\" in libc 5.0.9, not in 4.7.6
129 is available in libc5 and glibc and works without special defines.
130 Its prototype was given in
132 with libc5, but glibc does not provide a prototype.
133 This is bad, since a prototype is needed.
135 the above prototype, or something equivalent, to their own source.
136 When users complained about data loss caused by a miscompilation of
138 glibc 2.1.3 added the link-time warning
141 "the \`llseek\' function may be dangerous; use \`lseek64\' instead."
144 This makes this function unusable if one desires a warning-free
147 All the above functions are implemented in terms of this system call.
152 .BI "int _llseek(int " fd ", off_t " offset_hi ", off_t " offset_lo ,
153 .BI " loff_t *" result ", int " whence );
157 For more details, see
160 .SS Multithreading (see pthreads(7))
163 function is thread-safe.
168 This page is part of release 3.65 of the Linux
171 A description of the project,
172 and information about reporting bugs,
174 \%http://www.kernel.org/doc/man\-pages/.