136 lines
4.0 KiB
Groff
136 lines
4.0 KiB
Groff
.\"-
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.\" Copyright (c) 1990, 1993, 1994
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the Institute of Electrical and Electronics Engineers, Inc.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)sleep.1 8.3 (Berkeley) 4/18/94
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.\" $FreeBSD$
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.\"
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.Dd May 25, 2022
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.Dt SLEEP 1
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.Os
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.Sh NAME
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.Nm sleep
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.Nd suspend execution for an interval of time
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.Sh SYNOPSIS
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.Nm
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.Ar number Ns Op Ar unit
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.Ar ...
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.Sh DESCRIPTION
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The
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.Nm
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command suspends execution for a minimum of
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.Ar number
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seconds (the default, or unit
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.Cm s ) ,
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minutes (unit
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.Cm m ) ,
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hours (unit
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.Cm h ) ,
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or days (unit
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.Cm d ) .
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If multiple arguments are passed, the delay will be the sum of all values.
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.Pp
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If the
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.Nm
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command receives a signal, it takes the standard action.
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When the
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.Dv SIGINFO
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signal is received, the estimate of the amount of seconds left to
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sleep is printed on the standard output.
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.Sh IMPLEMENTATION NOTES
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The
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.Dv SIGALRM
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signal is not handled specially by this implementation.
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.Pp
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The
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.Nm
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command supports other time units than seconds,
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honors a non-integer number of time units to sleep in any form acceptable by
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.Xr strtod 3 ,
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and accepts more than one delay value.
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These are non-portable extensions, but they have also been implemented
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in GNU sh-utils since version 2.0a (released in 2002).
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.Sh EXIT STATUS
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.Ex -std
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.Sh EXAMPLES
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To schedule the execution of a command for
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.Va x
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number seconds later (with
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.Xr csh 1 ) :
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.Pp
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.Dl (sleep 1800; sh command_file >& errors)&
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.Pp
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This incantation would wait a half hour before
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running the script command_file.
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(See the
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.Xr at 1
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utility.)
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.Pp
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To reiteratively run a command (with the
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.Xr csh 1 ) :
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.Pp
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.Bd -literal -offset indent -compact
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while (1)
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if (! -r zzz.rawdata) then
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sleep 300
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else
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foreach i (`ls *.rawdata`)
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sleep 70
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awk -f collapse_data $i >> results
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end
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break
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endif
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end
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.Ed
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.Pp
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The scenario for a script such as this might be: a program currently
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running is taking longer than expected to process a series of
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files, and it would be nice to have
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another program start processing the files created by the first
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program as soon as it is finished (when zzz.rawdata is created).
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The script checks every five minutes for the file zzz.rawdata,
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when the file is found, then another portion processing
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is done courteously by sleeping for 70 seconds in between each
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awk job.
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.Sh SEE ALSO
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.Xr nanosleep 2 ,
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.Xr sleep 3
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.Sh STANDARDS
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The
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.Nm
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command is expected to be
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.St -p1003.2
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compatible.
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.Sh HISTORY
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A
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.Nm
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command appeared in
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.At v4 .
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