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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: .\" @(#)vwrite.2v 4.1 (Berkeley) 5/9/85
6: .\"
7: .TH VWRITE 2V deprecated
8: .UC 4
9: .SH NAME
10: vwrite \- write (virtually) to file
11: .SH SYNOPSIS
12: .nf
13: .B vwrite(filedes, buffer, nbytes)
14: .B char *buffer;
15: .fi
16: .SH DESCRIPTION
17: .B N.B.:
18: This call is likely to be replaced by more general virtual memory facilities
19: in the near future.
20: .PP
21: The
22: .I vwrite
23: system call is used in conjunction with
24: .I vread
25: to perform efficient updating of large files.
26: After a call to
27: .I vread
28: and updating of the data in the buffer which was given to
29: .I vread,
30: a
31: .I vwrite
32: of the same buffer to the same
33: .I filedes
34: at the same offset in the file
35: will cause data which has been modified since it was
36: .I vread
37: from (or
38: .I vwritten
39: to) the file to be returned to the file.
40: .SH SEE ALSO
41: vread(2)
42: .SH DIAGNOSTICS
43: Returns \-1 on error: bad descriptor, buffer address, count or alignment
44: as well as on physical I/O errors.
45: .SH BUGS
46: The result of
47: .I vwrite
48: is defined only when no other
49: .I vread's
50: have occurred on
51: .I buffer
52: since the one matching the
53: .I vwrite.
54: .PP
55: This call is peculiar to this version of UNIX.
56: It will be superseded by more general
57: virtual memory facilities in future versions of the system.
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