sleep/sleep.1

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  37 .\"     @(#)sleep.1     8.3 (Berkeley) 4/18/94
  38 .\"
  39 .Dd April 18, 1994
  40 .Dt SLEEP 1
  41 .Os
  42 .Sh NAME
  43 .Nm sleep
  44 .Nd suspend execution for an interval of time
  45 .Sh SYNOPSIS
  46 .Nm
  47 .Ar seconds
  48 .Sh DESCRIPTION
  49 The
  50 .Nm
  51 utility
  52 suspends execution for a minimum of
  53 .Ar seconds .
  54 It is usually used to schedule the execution of other commands (see
  55 .Sx EXAMPLES
  56 below).
  57 .Pp
  58 The
  59 .Nm
  60 utility exits with one of the following values:
  61 .Bl -tag -width flag
  62 .It Li \&0
  63 On successful completion, or if the signal
  64 .Dv SIGALRM
  65 was received.
  66 .It Li \&>\&0
  67 An error occurred.
  68 .El
  69 .Pp
  70 Note: The
  71 .Nx
  72 .Nm
  73 command will accept and honor a non-integer number of specified
  74 seconds. This is a non-portable extension, and its use will nearly
  75 guarantee that a shell script will not execute properly on another
  76 system.
  77 .Sh EXAMPLES
  78 To schedule the execution of a command for
  79 .Va x
  80 number seconds later:
  81 .Pp
  82 .Dl (sleep 1800; sh command_file >& errors)&
  83 .Pp
  84 This incantation would wait a half hour before
  85 running the script command_file. (See the
  86 .Xr at 1
  87 utility.)
  88 .Pp
  89 To reiteratively run a command (with the
  90 .Xr csh 1 ) :
  91 .Pp
  92 .Bd -literal -offset indent -compact
  93 while (1)
  94         if (! -r zzz.rawdata) then
  95                 sleep 300
  96         else
  97                 foreach i (`ls *.rawdata`)
  98                         sleep 70
  99                         awk -f collapse_data $i >> results
 100                 end
 101                 break
 102         endif
 103 end
 104 .Ed
 105 .Pp
 106 The scenario for a script such as this might be: a program currently
 107 running is taking longer than expected to process a series of
 108 files, and it would be nice to have
 109 another program start processing the files created by the first
 110 program as soon as it is finished (when zzz.rawdata is created).
 111 The script checks every five minutes for the file zzz.rawdata,
 112 when the file is found, then another portion processing
 113 is done courteously by sleeping for 70 seconds in between each
 114 awk job.
 115 .Sh SEE ALSO
 116 .Xr nanosleep 2 ,
 117 .Xr sleep 3 ,
 118 .Xr at 1
 119 .Sh STANDARDS
 120 The
 121 .Nm
 122 command is expected to be
 123 .St -p1003.2
 124 compatible.