sleep

Delay for a specified time.
Suspends execution for a minimum of seconds. Sleep is usually used to schedule the execution of other commands.

Syntax
      sleep seconds

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 command_file.

   To reiteratively run a command (with csh):

     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 running 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 created).

The script checks every five minutes for the file zzz.rawdata, when the file is found, then another portion processing is done courteously by sleeping for 70 seconds in between each awk job.

An alternative to sleep is setting the variable TMOUT, setting TMOUT=1200 will exit the shell if nothing is typed for 20 minutes. This can be a useful security fallback to ensure you don't remain logged on to a production server for too long.

Exits with 0 on successful completion, or if the signal SIGALRM was received.
exits with >0 if an error occurred.

“O sleep, O gentle sleep, nature's soft nurse, how have I frighted thee, that thou no more wilt weigh my eyelids down, and steep my senses in forgetfulness” ~ Shakespeare (Henry IV)

Related macOS commands:

setitimer(2)
at(1)


 
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