sleep/sleep.1

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  32 .\"     @(#)sleep.1     8.3 (Berkeley) 4/18/94
  33 .\" $FreeBSD: src/bin/sleep/sleep.1,v 1.22 2005/01/16 16:41:59 ru Exp $
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  35 .Dd April 18, 1994
  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
  45 The
  46 .Nm
  47 command
  48 suspends execution for a minimum of
  49 .Ar seconds .
  50 .Pp
  51 If the
  52 .Nm
  53 command receives a signal, it takes the standard action.
  54 .Sh IMPLEMENTATION NOTES
  55 The
  56 .Dv SIGALRM
  57 signal is not handled specially by this implementation.
  58 .Pp
  59 The
  60 .Nm
  61 command will accept and honor a non-integer number of specified seconds
  62 (with a
  63 .Ql .\&
  64 character as a decimal point).
  65 .Bf Sy
  66 This is a non-portable extension, and its use will nearly guarantee that
  67 a shell script will not execute properly on another system.
  68 .Ef
  69 .Sh EXIT STATUS
  70 .Ex -std
  71 .Sh EXAMPLES
  72 To schedule the execution of a command for
  73 .Va x
  74 number seconds later (with
  75 .Xr csh 1 ) :
  76 .Pp
  77 .Dl (sleep 1800; sh command_file >& errors)&
  78 .Pp
  79 This incantation would wait a half hour before
  80 running the script command_file.
  81 (See the
  82 .Xr at 1
  83 utility.)
  84 .Pp
  85 To reiteratively run a command (with the
  86 .Xr csh 1 ) :
  87 .Pp
  88 .Bd -literal -offset indent -compact
  89 while (1)
  90         if (! -r zzz.rawdata) then
  91                 sleep 300
  92         else
  93                 foreach i (`ls *.rawdata`)
  94                         sleep 70
  95                         awk -f collapse_data $i >> results
  96                 end
  97                 break
  98         endif
  99 end
 100 .Ed
 101 .Pp
 102 The scenario for a script such as this might be: a program currently
 103 running is taking longer than expected to process a series of
 104 files, and it would be nice to have
 105 another program start processing the files created by the first
 106 program as soon as it is finished (when zzz.rawdata is created).
 107 The script checks every five minutes for the file zzz.rawdata,
 108 when the file is found, then another portion processing
 109 is done courteously by sleeping for 70 seconds in between each
 110 awk job.
 111 .Sh SEE ALSO
 112 .Xr nanosleep 2 ,
 113 .Xr sleep 3
 114 .Sh STANDARDS
 115 The
 116 .Nm
 117 command is expected to be
 118 .St -p1003.2
 119 compatible.
 120 .Sh HISTORY
 121 A
 122 .Nm
 123 command appeared in
 124 .At v4 .