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.
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sleep NUMBER[SUFFIX] |
For example, to sleep for 30 seconds:
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sleep 30 |
To sleep for 2 minutes:
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sleep 2m |
To sleep for 1 hour:
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sleep 1h |
To sleep for 1 day:
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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.
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#!/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.
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sleep 2.5 |
Mohamed Ibrahim
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); }
