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 usually used to schedule the execution of other commands (see EXAMPLES below).

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 command_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 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.

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

STANDARDS
The sleep command is expected to be p1003.2 compatible.