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Annotation of 43BSDReno/lib/libc/sys/lseek.2, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1980 Regents of the University of California.
                      2: .\" All rights reserved.  The Berkeley software License Agreement
                      3: .\" specifies the terms and conditions for redistribution.
                      4: .\"
                      5: .\"    @(#)lseek.2     6.4 (Berkeley) 5/13/90
                      6: .\"
                      7: .TH LSEEK 2 "May 13, 1990"
                      8: .UC 4
                      9: .SH NAME
                     10: lseek \- move read/write pointer
                     11: .SH SYNOPSIS
                     12: .nf
                     13: .ft B
                     14: #include <unistd.h>
                     15: 
                     16: pos = lseek(d, offset, whence)
                     17: off_t pos;
                     18: int d;
                     19: off_t offset;
                     20: int whence;
                     21: .fi
                     22: .ft R
                     23: .SH DESCRIPTION
                     24: The descriptor 
                     25: .I d
                     26: refers to a file or device open for reading and/or writing.
                     27: .I Lseek
                     28: sets the file pointer of
                     29: .I d
                     30: as follows:
                     31: .IP
                     32: If
                     33: .I whence
                     34: is SEEK_SET, the pointer is set to
                     35: .I offset
                     36: bytes.
                     37: .IP
                     38: If
                     39: .I whence
                     40: is SEEK_CUR, the pointer is set to its current location plus
                     41: .IR offset .
                     42: .IP
                     43: If
                     44: .I whence
                     45: is SEEK_END, the pointer is set to the size of the
                     46: file plus
                     47: .IR offset .
                     48: .PP
                     49: Upon successful completion, the resulting pointer location
                     50: as measured in bytes from beginning of the file is returned.
                     51: Some devices are incapable of seeking.  The value of the pointer
                     52: associated with such a device is undefined.
                     53: .SH NOTES
                     54: Seeking far beyond the end of a file, then writing,
                     55: creates a gap or \*(lqhole\*(rq, which occupies no
                     56: physical space and reads as zeros.
                     57: .SH "RETURN VALUE
                     58: Upon successful completion,
                     59: the current file pointer value is returned.
                     60: Otherwise,
                     61: a value of \-1 is returned and \fIerrno\fP is set to indicate
                     62: the error.
                     63: .SH "ERRORS
                     64: .I Lseek
                     65: will fail and the file pointer will remain unchanged if:
                     66: .TP 15
                     67: [EBADF]
                     68: .I Fildes
                     69: is not an open file descriptor.
                     70: .TP 15
                     71: [ESPIPE]
                     72: .I Fildes
                     73: is associated with a pipe or a socket.
                     74: .TP 15
                     75: [EINVAL]
                     76: .I Whence
                     77: is not a proper value.
                     78: .SH "SEE ALSO"
                     79: dup(2), open(2)
                     80: .SH BUGS
                     81: This document's use of
                     82: .I whence
                     83: is incorrect English, but maintained for historical reasons.

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