sleep -- suspend execution for an interval of time
The sleep command suspends execution for a minimum of seconds.
If the sleep command receives a signal, it takes the standard action.
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.
To schedule the execution of a command for x number seconds later (with
(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)):
if (! -r zzz.rawdata) then
foreach i (`ls *.rawdata`)
awk -f collapse_data $i >> results
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.
The sleep utility exits 0 on success, and >0 if an error occurs.
The sleep command is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.
A sleep command appeared in Version 4 AT&T UNIX.
FreeBSD 5.2.1 April 18, 1994 FreeBSD 5.2.1 [ Back ]