.\"
.\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for
.\" permission to reproduce portions of its copyrighted documentation.
.\" Original documentation from The Open Group can be obtained online at
.\" http://www.opengroup.org/bookstore/.
.\"
.\" The Institute of Electrical and Electronics Engineers and The Open
.\" Group, have given us permission to reprint portions of their
.\" documentation.
.\"
.\" In the following statement, the phrase ``this text'' refers to portions
.\" of the system documentation.
.\"
.\" Portions of this text are reprinted and reproduced in electronic form
.\" in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
.\" Standard for Information Technology -- Portable Operating System
.\" Interface (POSIX), The Open Group Base Specifications Issue 6,
.\" Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
.\" Engineers, Inc and The Open Group.  In the event of any discrepancy
.\" between these versions and the original IEEE and The Open Group
.\" Standard, the original IEEE and The Open Group Standard is the referee
.\" document.  The original Standard can be obtained online at
.\" http://www.opengroup.org/unix/online.html.
.\"
.\" This notice shall appear on any product containing this material.
.\"
.\" The contents of this file are subject to the terms of the
.\" Common Development and Distribution License (the "License").
.\" You may not use this file except in compliance with the License.
.\"
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
.\" or http://www.opensolaris.org/os/licensing.
.\" See the License for the specific language governing permissions
.\" and limitations under the License.
.\"
.\" When distributing Covered Code, include this CDDL HEADER in each
.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
.\" If applicable, add the following below this CDDL HEADER, with the
.\" fields enclosed by brackets "[]" replaced with your own identifying
.\" information: Portions Copyright [yyyy] [name of copyright owner]
.\"
.\"
.\" Copyright 1989 AT&T
.\" Portions Copyright (c) 1992, X/Open Company Limited  All Rights Reserved
.\" Portions Copyright (c) 1982-2007 AT&T Knowledge Ventures
.\" Copyright (c) 2007, Sun Microsystems, Inc.  All Rights Reserved  Portions
.\"
.TH SLEEP 1 "May 13, 2017"
.SH NAME
sleep \- suspend execution for an interval
.SH SYNOPSIS
.SS "/usr/bin/sleep"
.LP
.nf
\fB/usr/bin/sleep\fR \fIseconds\fR
.fi

.SS "ksh93"
.LP
.nf
\fBsleep\fR \fIseconds\fR
.fi

.SH DESCRIPTION
.LP
\fBsleep\fR suspends execution for at least the time in seconds specified by
\fIseconds\fR or until a \fBSIGALRM\fR signal is received. The \fIseconds\fR
operand can be specified as a floating point number but the actual granularity
normally depends on the underlying system.
.SH OPERANDS
.SS "/usr/bin/sleep"
.LP
The following operands are supported for \fB/usr/bin/sleep\fR and \fBksh93\fR's
\fBsleep\fR built-in command:
.sp
.ne 2
.na
\fB\fIseconds\fR\fR
.ad
.RS 11n
A non-negative floating-point number specifying the number of seconds for which
to suspend execution. The floating-point number may be specified in all formats
required by C99/XPG6, including constants such as "Inf" or "infinity".
.RE

.SS "ksh93"
.LP
The following operands are supported:
.sp
.ne 2
.na
\fB\fItime\fR\fR
.ad
.RS 8n
Specify \fItime\fR in seconds as a floating point number. The actual
granularity depends on the underlying system, normally around 1 millisecond.
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fRSuspending Command Execution
.sp
.LP
The following example executes a command after a certain amount of time:

.sp
.in +2
.nf
example% \fB(sleep 105; \fIcommand\fR)&\fR
.fi
.in -2
.sp

.LP
\fBExample 2 \fRExecuting a Command Every So Often
.sp
.LP
The following example executes a command every so often:

.sp
.in +2
.nf
example% \fBwhile true
do
        \fIcommand\fR
        sleep 37
done\fR
.fi
.in -2
.sp

.LP
\fBExample 3 \fRSuspend command execution forever (or until a \fBSIGALRM\fR
signal is received)
.sp
.in +2
.nf
example% sleep Inf
.fi
.in -2
.sp

.LP
\fBExample 4 \fRSuspending command execution for 0.5 seconds
.sp
.LP
Suspending command execution for 0.5 seconds using an alternative
floating-point representation for the value "0.5"

.sp
.in +2
.nf
example% printf "%a\en" 0.5
0x1.0000000000000000000000000000p-01
.fi
.in -2
.sp

.sp
.in +2
.nf
example% sleep 0x1.0000000000000000000000000000p-01
.fi
.in -2
.sp

.SH ENVIRONMENT VARIABLES
.LP
See \fBenviron\fR(5) for descriptions of the following environment variables
that affect the execution of \fBsleep\fR: \fBLANG\fR, \fBLC_ALL\fR,
\fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
.SH EXIT STATUS
.LP
The following exit values are returned:
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 6n
The execution was successfully suspended for at least \fItime\fR seconds, or a
\fBSIGALRM\fR signal was received (see NOTES).
.RE

.sp
.ne 2
.na
\fB\fB>0\fR\fR
.ad
.RS 6n
An error has occurred.
.RE

.SH ATTRIBUTES
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.SS "/usr/bin/sleep"
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
Standard	See \fBstandards\fR(5).
.TE

.SS "ksh93"
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Uncommitted
.TE

.SH SEE ALSO
.LP
\fBksh93\fR(1), \fBwait\fR(1), \fBalarm\fR(2), \fBsleep\fR(3C),
\fBattributes\fR(5), \fBenviron\fR(5), \fBstandards\fR(5)
.SH NOTES
.LP
If the \fBsleep\fR utility receives a \fBSIGALRM\fR signal, one of the
following actions is taken:
.RS +4
.TP
.ie t \(bu
.el o
Terminate normally with a zero exit status.
.RE
.RS +4
.TP
.ie t \(bu
.el o
Effectively ignore the signal.
.RE
.sp
.LP
The \fBsleep\fR utility takes the standard action for all other signals.
.sp
.LP
The behavior for input values such as "NaN" (not-a-number) or negative values
is undefined.