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 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 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.

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

"I think men talk to women so they can sleep with them and women sleep with men so they can talk to them" - Jay McInerney

Related:

sleep man page - Apple.com
setitimer(2)
at(1)