sleep(1) - NetBSD Manual Pages

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SLEEP(1)                    NetBSD Reference Manual                   SLEEP(1)


NAME

     sleep - suspend execution for an interval of time


SYNOPSIS

     sleep seconds


DESCRIPTION

     The sleep utility suspends execution for a minimum of seconds. It is usu-
     ally used to schedule the execution of other commands (see EXAMPLES be-
     low).

     The sleep utility exits with one of the following values:

     0     On successful completion, or if the signal SIGALRM was received.

     >0    An error occurred.

     Note: The NetBSD sleep command will accept and honor a non-integer number
     of specified seconds. This is a non-portable extension, and its use will
     nearly guarantee that a shell script will not execute properly on another
     system.


EXAMPLES

     To schedule the execution of a command for x number seconds later:

           (sleep 1800; sh command_file >& errors)&

     This incantation would wait a half hour before running the script com-
     mand_file. (See the at(1) utility.)

     To reiteratively run a command (with the csh(1)):

           while (1)
                   if (! -r zzz.rawdata) then
                           sleep 300
                   else
                           foreach i (`ls *.rawdata`)
                                   sleep 70
                                   awk -f collapse_data $i >> results
                           end
                           break
                   endif
           end

     The scenario for a script such as this might be: a program currently run-
     ning is taking longer than expected to process a series of files, and it
     would be nice to have another program start processing the files created
     by the first program as soon as it is finished (when zzz.rawdata is cre-
     ated).  The script checks every five minutes for the file zzz.rawdata,
     when the file is found, then another portion processing is done courte-
     ously by sleeping for 70 seconds in between each awk job.


SEE ALSO

     nanosleep(2),  sleep(3),  at(1)


STANDARDS

     The sleep command is expected to be IEEE Std1003.2 (``POSIX.2'') compati-
     ble.

4.4BSD                          April 18, 1994                               1