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[dragonfly.git] / lib / libc / gen / usleep.3
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32.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: src/lib/libc/gen/usleep.3,v 1.10.2.7 2001/12/14 18:33:51 ru Exp $
1de703da 34.\" $DragonFly: src/lib/libc/gen/usleep.3,v 1.2 2003/06/17 04:26:42 dillon Exp $
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35.\"
36.Dd February 13, 1998
37.Dt USLEEP 3
38.Os
39.Sh NAME
40.Nm usleep
41.Nd suspend process execution for an interval measured in microseconds
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In unistd.h
46.Ft int
47.Fn usleep "unsigned int microseconds"
48.Sh DESCRIPTION
49The
50.Fn usleep
51function suspends execution of the calling process until either
52.Fa microseconds
53microseconds have elapsed or a signal is delivered to the process and its
54action is to invoke a signal-catching function or to terminate the
55process.
56System activity may lengthen the sleep by an indeterminate amount.
57.Pp
58This function is implemented using
59.Xr nanosleep 2
60by pausing for
61.Fa microseconds
62microseconds or until a signal occurs.
63Consequently, in this implementation,
64sleeping has no effect on the state of process timers,
65and there is no special handling for SIGALRM.
66.Sh RETURN VALUES
67.Rv -std usleep
68.Sh ERRORS
69The
70.Fn usleep
71function
72will fail if:
73.Bl -tag -width Er
74.It Bq Er EINTR
75A signal was delivered to the process and its
76action was to invoke a signal-catching function.
77.El
78.Sh SEE ALSO
79.Xr nanosleep 2 ,
80.Xr sleep 3
81.Sh HISTORY
82The
83.Fn usleep
84function appeared in
85.Bx 4.3 .