SLEEP(1) | General Commands Manual | SLEEP(1) |
sleep
— suspend
execution for an interval of time
sleep |
seconds |
The sleep
command suspends execution for a
minimum of seconds.
If the sleep
command receives a signal, it
takes the standard action. When the SIGINFO
signal
is received, the estimate of the amount of seconds left to sleep is printed
on the standard output.
The SIGALRM
signal is not handled
specially by this implementation.
The sleep
command allows and honors a
non-integer number of seconds to sleep in any form acceptable by
strtod(3). This is a non-portable
extension, but is also implemented in GNU sh-utils since version 2.0a
(released in 2002).
The sleep
utility exits 0 on
success, and >0 if an error occurs.
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 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.
The sleep
command is expected to be
IEEE Std 1003.2 (“POSIX.2”)
compatible.
A sleep
command appeared in
Version 4 AT&T UNIX.
December 31, 2020 | macOS 14.6 |