1.\"- 2.\" Copyright (c) 1990, 1993, 1994 3.\" The Regents of the University of California. All rights reserved. 4.\" 5.\" This code is derived from software contributed to Berkeley by 6.\" the Institute of Electrical and Electronics Engineers, Inc. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)sleep.1 8.3 (Berkeley) 4/18/94 33.\" $FreeBSD$ 34.\" 35.Dd December 31, 2020 36.Dt SLEEP 1 37.Os 38.Sh NAME 39.Nm sleep 40.Nd suspend execution for an interval of time 41.Sh SYNOPSIS 42.Nm 43.Ar seconds 44.Sh DESCRIPTION 45The 46.Nm 47command 48suspends execution for a minimum of 49.Ar seconds . 50.Pp 51If the 52.Nm 53command receives a signal, it takes the standard action. 54When the 55.Dv SIGINFO 56signal is received, the estimate of the amount of seconds left to 57sleep is printed on the standard output. 58.Sh IMPLEMENTATION NOTES 59The 60.Dv SIGALRM 61signal is not handled specially by this implementation. 62.Pp 63The 64.Nm 65command allows and honors a non-integer number of seconds to sleep 66in any form acceptable by 67.Xr strtod 3 . 68This is a non-portable extension, but is also implemented in GNU sh-utils 69since version 2.0a (released in 2002). 70.Sh EXIT STATUS 71.Ex -std 72.Sh EXAMPLES 73To schedule the execution of a command for 74.Va x 75number seconds later (with 76.Xr csh 1 ) : 77.Pp 78.Dl (sleep 1800; sh command_file >& errors)& 79.Pp 80This incantation would wait a half hour before 81running the script command_file. 82(See the 83.Xr at 1 84utility.) 85.Pp 86To reiteratively run a command (with the 87.Xr csh 1 ) : 88.Pp 89.Bd -literal -offset indent -compact 90while (1) 91 if (! -r zzz.rawdata) then 92 sleep 300 93 else 94 foreach i (`ls *.rawdata`) 95 sleep 70 96 awk -f collapse_data $i >> results 97 end 98 break 99 endif 100end 101.Ed 102.Pp 103The scenario for a script such as this might be: a program currently 104running is taking longer than expected to process a series of 105files, and it would be nice to have 106another program start processing the files created by the first 107program as soon as it is finished (when zzz.rawdata is created). 108The script checks every five minutes for the file zzz.rawdata, 109when the file is found, then another portion processing 110is done courteously by sleeping for 70 seconds in between each 111awk job. 112.Sh SEE ALSO 113.Xr nanosleep 2 , 114.Xr sleep 3 115.Sh STANDARDS 116The 117.Nm 118command is expected to be 119.St -p1003.2 120compatible. 121.Sh HISTORY 122A 123.Nm 124command appeared in 125.At v4 . 126