xref: /freebsd/lib/libsys/sleep.3 (revision 8e95079e175854b84e57c521b34b4b52f7ae9cb1)
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28.Dd February 13, 1998
29.Dt SLEEP 3
30.Os
31.Sh NAME
32.Nm sleep
33.Nd suspend thread execution for an interval measured in seconds
34.Sh LIBRARY
35.Lb libc
36.Sh SYNOPSIS
37.In unistd.h
38.Ft unsigned int
39.Fn sleep "unsigned int seconds"
40.Sh DESCRIPTION
41The
42.Fn sleep
43function suspends execution of the calling thread until either
44.Fa seconds
45seconds have elapsed or a signal is delivered to the thread and its
46action is to invoke a signal-catching function or to terminate the
47thread or process.
48System activity may lengthen the sleep by an indeterminate amount.
49.Pp
50This function is implemented using
51.Xr nanosleep 2
52by pausing for
53.Fa seconds
54seconds or until a signal occurs.
55Consequently, in this implementation,
56sleeping has no effect on the state of process timers,
57and there is no special handling for SIGALRM.
58.Sh RETURN VALUES
59If the
60.Fn sleep
61function returns because the requested time has elapsed, the value
62returned will be zero.
63If the
64.Fn sleep
65function returns due to the delivery of a signal, the value returned
66will be the unslept amount (the requested time minus the time actually
67slept) in seconds.
68.Sh SEE ALSO
69.Xr nanosleep 2 ,
70.Xr usleep 3
71.Sh STANDARDS
72The
73.Fn sleep
74function conforms to
75.St -p1003.1-90 .
76.Sh HISTORY
77A
78.Fn sleep
79function appeared in
80.At v7 .
81