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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) %G% | |
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56 | It will be superseded by more general | |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. |