sleep(1) General Commands Manual sleep(1)
sleep - Suspends execution for at least the specified time
Interfaces documented on this reference page conform to industry standards as follows:
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Non-negative integer specifying the number of seconds for which execution is to be suspended.
The sleep command suspends execution of a process for at least the interval specified by seconds, which can range from 0 to 2,147,483,647
seconds. Depending on system activity, the actual time of suspension may be longer. See the sleep(3) reference page.
[Tru64 UNIX] seconds can be entered as a non-negative decimal, octal, or hexadecimal value.
If sleep receives a SIGALARM signal before process execution has resumed, sleep takes one of the following actions: Terminates normally
with a 0 (zero) exit status. (See the sleep(3) reference page for more information.) Ignores the signal Performs default processing
The following exit values are returned: Execution was successfully suspended for at least the requested time, or a SIGALARM signal was
received. An error occurred.
To display a message at 4-minute intervals for 20 minutes, create a shell script called remind containing the following:
for i do sleep 240; echo $i sleep 240; echo $i sleep 240; echo $i sleep 240; echo $i sleep 240; echo $i done
To display the message Try calling NHK at 4-minute intervals, enter: remind 'Try calling NHK' To run a command at regular intervals,
create a shell script containing the following:
while true do
sleep 60 done
This displays the date and time once a minute. To execute a command after a specified interval, enter the following; (sleep 3600;
echo Time's up) &
This displays the message "Time's up" after one hour.
The following environment variables affect the execution of sleep: Provides a default value for the internationalization variables that are
unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization vari-
ables contain an invalid setting, the utility behaves as if none of the variables had been defined. If set to a non-empty string value,
overrides the values of all the other internationalization variables. Determines the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as opposed to multibyte characters in arguments). Determines the locale for the for-
mat and contents of diagnostic messages written to standard error. Determines the location of message catalogues for the processing of
Functions: alarm(3), pause(3), sigaction(2), sleep(3)