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NAME

sleep — suspend execution for an interval of time

SYNOPSIS

DESCRIPTION

The sleep utility suspends execution for a minimum of the specified number of seconds. This number must be positive and may contain a decimal fraction. sleep is commonly used to schedule the execution of other commands (see below).

ASYNCHRONOUS EVENTS

SIGALRM

Terminate normally, with a zero exit status.

EXIT STATUS

The sleep utility exits 0 on success, and >0 if an error occurs.

EXAMPLES

Wait a half hour before running the script command_file (see also the at(1) utility):

To repetitively run a command (with csh(1)):

while (! -r zzz.rawdata)
	sleep 300
end
foreach i (*.rawdata)
	sleep 70
	awk -f collapse_data $i >> results
end

The scenario for such a script 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 this file. When it is found, processing is done in several steps by sleeping 70 seconds between each awk(1) job.

To monitor the growth of a file without consuming too many resources:

while true; do
	ls -l file
	sleep 5
done

SEE ALSO

at(1)

STANDARDS

The sleep utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification.

The handling of fractional arguments is provided as an extension to that specification.

HISTORY

A sleep utility appeared in Version 4 AT&T UNIX.