DragonFly On-Line Manual Pages


SLEEP(1)	       DragonFly General Commands Manual	      SLEEP(1)

NAME

sleep -- suspend execution for an interval of time

SYNOPSIS

sleep seconds

DESCRIPTION

The sleep command suspends execution for a minimum of seconds. If the sleep command receives a signal, it takes the standard action.

IMPLEMENTATION NOTES

The SIGALRM signal is not handled specially by this implementation. The sleep command will accept and honor a non-integer number of specified seconds (with a `.' character as a decimal point). This is a non-porta- ble extension, and its use will nearly guarantee that a shell script will not execute properly on another system.

EXIT STATUS

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

EXAMPLES

To schedule the execution of a command for x number seconds later (with csh(1)): (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)

STANDARDS

The sleep command is expected to be IEEE Std 1003.2 (``POSIX.2'') compat- ible.

HISTORY

A sleep command appeared in Version 4 AT&T UNIX. DragonFly 3.7 April 18, 1994 DragonFly 3.7