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28 .\" @(#)lseek.2 8.3 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/lib/libc/sys/lseek.2,v 1.10.2.6 2001/12/14 18:34:01 ru Exp $
30 .\" $DragonFly: src/lib/libc/sys/lseek.2,v 1.3 2006/02/17 19:35:06 swildner Exp $
37 .Nd reposition read/write file offset
43 .Fn lseek "int fildes" "off_t offset" "int whence"
47 function repositions the offset of the file descriptor
52 according to the directive
59 repositions the file position pointer associated with the file
63 .Bl -item -offset indent
77 the offset is set to its current location plus
85 the offset is set to the size of the
93 function allows the file offset to be set beyond the end
94 of the existing end-of-file of the file.
95 If data is later written
96 at this point, subsequent reads of the data in the gap return
97 bytes of zeros (until data is actually written into the gap).
99 Some devices are incapable of seeking. The value of the pointer
100 associated with such a device is undefined.
102 Upon successful completion,
104 returns the resulting offset location as measured in bytes from the
105 beginning of the file.
107 a value of -1 is returned and
113 will fail and the file position pointer will remain unchanged if:
117 is not an open file descriptor.
120 is associated with a pipe, socket, or FIFO.
123 is not a proper value.
131 function call is expected to conform to
136 function call appeared in
139 This document's use of
141 is incorrect English, but is maintained for historical reasons.