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| 28 | .\" @(#)usleep.3 8.1 (Berkeley) 6/4/93 |
| 29 | .\" $FreeBSD: src/lib/libc/gen/usleep.3,v 1.19 2007/01/09 00:27:56 imp Exp $ |
| 30 | .\" |
| 31 | .Dd February 13, 1998 |
| 32 | .Dt USLEEP 3 |
| 33 | .Os |
| 34 | .Sh NAME |
| 35 | .Nm usleep |
| 36 | .Nd suspend thread execution for an interval measured in microseconds |
| 37 | .Sh LIBRARY |
| 38 | .Lb libc |
| 39 | .Sh SYNOPSIS |
| 40 | .In unistd.h |
| 41 | .Ft int |
| 42 | .Fo usleep |
| 43 | .Fa "useconds_t useconds" |
| 44 | .Fc |
| 45 | .Sh DESCRIPTION |
| 46 | The |
| 47 | .Fn usleep |
| 48 | function suspends execution of the calling thread until either |
| 49 | .Fa useconds |
| 50 | microseconds have elapsed |
| 51 | or a signal is delivered to the thread whose action |
| 52 | is to invoke a signal-catching function |
| 53 | or to terminate the thread or process. |
| 54 | The actual time slept may be longer, due to system latencies |
| 55 | and possible limitations in the timer resolution of the hardware. |
| 56 | .Pp |
| 57 | This function is implemented, using |
| 58 | .Xr nanosleep 2 , |
| 59 | by pausing for |
| 60 | .Fa useconds |
| 61 | microseconds or until a signal occurs. |
| 62 | Consequently, in this implementation, |
| 63 | sleeping has no effect on the state of process timers |
| 64 | and there is no special handling for SIGALRM. |
| 65 | .Sh RETURN VALUES |
| 66 | .Rv -std usleep |
| 67 | .Sh ERRORS |
| 68 | The |
| 69 | .Fn usleep |
| 70 | function |
| 71 | will fail if: |
| 72 | .Bl -tag -width Er |
| 73 | .It Bq Er EINTR |
| 74 | A signal was delivered to the process and its |
| 75 | action was to invoke a signal-catching function. |
| 76 | .El |
| 77 | .Sh SEE ALSO |
| 78 | .Xr nanosleep 2 , |
| 79 | .Xr sleep 3 |
| 80 | .Sh HISTORY |
| 81 | The |
| 82 | .Fn usleep |
| 83 | function appeared in |
| 84 | .Bx 4.3 . |