How to Sleep in Shell Script

Sometimes you will need to pause execution for a specific period within a shell script. To do that, you will need to use the sleep command to delay for a specified amount of time in seconds, minutes, hours or days.

To pause using the sleep command, pass the amount of time that has to paused as arguments to the command. This argument is a number indicating the number of seconds to sleep. The argument can include an optional suffix that may be ‘s’ for seconds (the default), ‘m’ for minutes, ‘h’ for hours or ‘d’ for days.

sleep NUMBER[SUFFIX]

For example, to sleep for 30 seconds:

sleep 30

To sleep for 2 minutes:

sleep 2m

To sleep for 1 hour:

sleep 1h

To sleep for 1 day:

sleep 1d

When do you use the sleep command

Let’s say that you will need to continuously monitor a process and that some actions have to be performed in the event that the process is no longer running. If you use a shell script to check on the process continuously in a loop, there is a very high chance that the script will introduce a slight increase in the CPU load. If you include the sleep command within the loop the CPU increase will most probably be negligible.

#!/bin/bash
process_name=some_process_name

while true ; do
ps -C $process_name
[ $? -ne 0 ] && echo "warning: process not running"
sleep 1m
done

Sleep with millisecond precision

Normally, GNU versions of sleep allow you to specify a floating number instead of just an integer for the sleep duration. So you can specify sleep durations of 2.5 seconds, 10.1 seconds, etc.

sleep 2.5

ibrahim = { interested_in(unix, linux, android, open_source, reverse_engineering); coding(c, shell, php, python, java, javascript, nodejs, react); plays_on(xbox, ps4); linux_desktop_user(true); }