projects / unix-history / blame
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|---|---|---|
| cb026509 KM |
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 | .\" | |
| 95f51977 | 5 | .\" @(#)@(#)usleep.3 6.3 (Berkeley) 5/15/86 |
| cb026509 | 6 | .\" |
| 95f51977 | 7 | .TH USLEEP 3 "May 15, 1986" |
| cb026509 KM |
8 | .UC 6 |
| 9 | .SH NAME | |
| 10 | usleep \- suspend execution for interval | |
| 11 | .SH SYNOPSIS | |
| 12 | .nf | |
| 13 | .B usleep(useconds) | |
| 14 | .B unsigned useconds; | |
| 15 | .fi | |
| 16 | .SH DESCRIPTION | |
| 17 | The current process is suspended from execution for the number | |
| 18 | of microseconds specified by the argument. | |
| 19 | The actual suspension time may be an arbitrary amount longer | |
| d9d2c099 MK |
20 | because of other activity in the system |
| 21 | or because of the time spent in processing the call. | |
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22 | .PP |
| 23 | The routine is implemented by setting an interval timer | |
| 24 | and pausing until it occurs. | |
| 25 | The previous state of this timer is saved and restored. | |
| 26 | If the sleep time exceeds the time to the expiration of the | |
| 27 | previous timer, | |
| 28 | the process sleeps only until the signal would have occurred, and the | |
| d9d2c099 MK |
29 | signal is sent a short time later. |
| 30 | .PP | |
| 31 | This routine is implemented using | |
| 32 | .IR setitimer (2); | |
| 33 | it requires eight system calls each time it is invoked. | |
| 34 | A similar but less compatible function can be obtained with a single | |
| 35 | .IR select (2); | |
| 36 | it would not restart after signals, but would not interfere | |
| 37 | with other uses of | |
| 38 | .IR setitimer . | |
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39 | .SH "SEE ALSO" |
| 40 | setitimer(2), getitimer(2), sigpause(2), ualarm(3), sleep(3), alarm(3) |