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1 | .\" Copyright (c) 1986, 1991 Regents of the University of California. |
2 | .\" All rights reserved. | |
3 | .\" | |
4 | .\" Redistribution and use in source and binary forms, with or without | |
5 | .\" modification, are permitted provided that the following conditions | |
6 | .\" are met: | |
7 | .\" 1. Redistributions of source code must retain the above copyright | |
8 | .\" notice, this list of conditions and the following disclaimer. | |
9 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
10 | .\" notice, this list of conditions and the following disclaimer in the | |
11 | .\" documentation and/or other materials provided with the distribution. | |
12 | .\" 3. All advertising materials mentioning features or use of this software | |
13 | .\" must display the following acknowledgement: | |
14 | .\" This product includes software developed by the University of | |
15 | .\" California, Berkeley and its contributors. | |
16 | .\" 4. Neither the name of the University nor the names of its contributors | |
17 | .\" may be used to endorse or promote products derived from this software | |
18 | .\" without specific prior written permission. | |
19 | .\" | |
20 | .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
21 | .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
22 | .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
23 | .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
24 | .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
25 | .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
26 | .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
27 | .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
28 | .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
29 | .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
30 | .\" SUCH DAMAGE. | |
31 | .\" | |
32 | .\" @(#)sleep.3 6.3 (Berkeley) 4/19/91 | |
33 | .\" | |
34 | .Dd April 19, 1991 | |
35 | .Dt SLEEP 3 | |
36 | .Os | |
37 | .Sh NAME | |
38 | .Nm sleep | |
39 | .Nd suspend process execution for interval of seconds | |
40 | .Sh SYNOPSIS | |
41 | .Fd #include <unistd.h> | |
42 | .Ft int | |
43 | .Fn sleep "u_int seconds" | |
44 | .Sh DESCRIPTION | |
45 | The | |
46 | .Fn sleep | |
47 | function | |
48 | suspends execution of the calling process | |
49 | for | |
50 | .Fa seconds | |
51 | of time. | |
52 | System activity or time spent in processing the | |
53 | call may lengthen the sleep by a second. | |
54 | .Pp | |
55 | If a timer is already running on the process its state is saved. | |
56 | If the value | |
57 | .Fa seconds | |
58 | is more than or equal to the remaining clock time for the saved timer, | |
59 | the sleep time is set to | |
60 | the remaining clock time. | |
61 | The state of the previous timer | |
62 | is restored after | |
63 | .Fa seconds | |
64 | has passed. | |
65 | .Pp | |
66 | This function is implemented using | |
67 | .Xr setitimer 2 ; | |
68 | it requires eight system calls each time it is invoked. | |
69 | A similar but less compatible function can be obtained with a single | |
70 | .Xr select 2 ; | |
71 | such a function would not restart after signals, but would not interfere | |
72 | with other uses of | |
73 | .Xr setitimer . | |
74 | .Sh RETURN VALUES | |
75 | .Sh SEE ALSO | |
76 | .Xr setitimer 2 , | |
77 | .Xr sigpause 2 , | |
78 | .Xr usleep 3 | |
79 | .Sh HISTORY | |
80 | A | |
81 | .Fn sleep | |
82 | function appeared in | |
83 | .At v7 . |