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1.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>.
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3.\"
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28.\" $FreeBSD: src/lib/libc_r/man/sigwait.3,v 1.7 2001/10/01 16:09:09 ru Exp $
29.Dd April 27, 2000
30.Dt SIGWAIT 2
31.Os
32.Sh NAME
33.Nm sigwait
34.Nd select a set of signals
35.Sh SYNOPSIS
36.In signal.h
37.Ft int
224c7076 38.Fn sigwait "const sigset_t *restrict set" "int *restrict sig"
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39.Sh DESCRIPTION
40The
41.Fn sigwait
42function selects a set of signals, specified by
43.Fa set .
44If none of the selected signals are pending,
45.Fn sigwait
46waits until one or more of the selected signals has been generated.
47Then
48.Fn sigwait
49atomically clears one of the selected signals from the set of pending signals
50for the process and sets the location pointed to by
51.Fa sig
52to the signal number that was cleared.
53.Pp
54The signals specified by
55.Fa set
9385eb3d 56should be blocked, but not ignored, at the time of the call to
5b2abdfb 57.Fn sigwait .
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58.Pp
59Processes which call
60.Fn sigwait
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61on ignored signals will wait indefinitely. Ignored
62signals are dropped immediately by the system, before delivery
9385eb3d 63to a waiting process.
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64.Sh RETURN VALUES
65If successful,
66.Fn sigwait
67returns 0 and sets the location pointed to by
68.Fa sig
69to the cleared signal number.
70Otherwise, an error number is returned.
71.Sh ERRORS
72.Fn sigwait
73will fail if:
74.Bl -tag -width Er
75.It Bq Er EINVAL
76.Fa set
77specifies one or more invalid signal numbers.
78.El
79.Sh SEE ALSO
224c7076 80.Xr pthread_sigmask 2 ,
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81.Xr sigaction 2 ,
82.Xr sigpending 2 ,
83.Xr sigsuspend 2 ,
224c7076 84.Xr pause 3
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85.Sh STANDARDS
86.Fn sigwait
87conforms to ISO/IEC 9945-1:1996 (``POSIX.1'')