The Bash sleep command delays the execution of the command after it for a given amount of time. The sleep time is expressed in seconds. The use of the sleep command is common when scheduling a task every X seconds or when a script relies on another script to complete its execution.

These are three scenarios in which you would use the sleep command:

Let’s get started!

The basic syntax of the sleep command in Bash is very simple:

Here is what happens if you run it in the command line:

In this case, after executing the sleep 5 command Linux returns the shell back after 5 seconds.

Now let’s move to three practical examples of how to you the Bash sleep command.

I will write a simple Bash shell script to show the exact behavior of the sleep command…

…considering that the previous example couldn’t show that the sleep command returned the shell after 5 seconds.

Let’s write a script that does what I have explained in Scenario 1, it delays the execution of a command by X seconds (in this case 5 seconds).

It’s almost like executing a command at a specific time following the same principle of job schedulers.

So, create a very simple Bash shell script called delay_cmd.sh:

The date command is used to print the current date before and after the sleep command, in this way, you can see that the script is suspended for 5 seconds.

After 5 seconds the uptime command is executed.

Makes sense?

In theory, we can write the same script in a single line:

This is because the semicolon is used in Linux to separate different commands and execute them sequentially.

In other words, Linux makes sure each command completes before executing the next one.

In this example, I will create two scripts:

Here is program_1.sh:

The touch command is used by the first program to create the stage1.complete file after 30 seconds from the moment the script is executed.

And program_2.sh is the following, we will be using a Bash if else statement to implement it:

In the second Bash shell script, we have an infinite loop. At every iteration of the script:

Before executing the two scripts make sure they are both executable using the chmod +x command:

So, let’s run the scripts…

We will run program_1.sh first, we will run it in the background so that we can run program_2.sh immediately after that in the same terminal:

As expected the second script keeps sleeping for 6 seconds until it finds the file stage1.complete file, and then it stops its execution.

If you want to call an API using a Bash script you can use the curl command.

Using curl to call an API is simple, let’s take for example the following API endpoint:

We will write a Bash script that uses curl to perform a GET request against it and uses the sleep command to limit the number of API calls in a certain period of time.

This is done to avoid going over any potential limits imposed by the API provider.

This is the script I have written:

A few things about this script:

So, execute the script:

As expected two API calls are executed and then the execution of the while loop stops because the value of the variable COUNTER is 3.

I showed you different ways to use the sleep command in a Bash script.

And in the process I have covered a lot of different things:

I hope it makes all sense!

And you? How else would you use the sleep command in Bash? 🙂

Related FREE Course: Decipher Bash Scripting

Claudio Sabato is an IT expert with over 15 years of professional experience in Python programming, Linux Systems Administration, Bash programming, and IT Systems Design. He is a professional certified by the Linux Professional Institute.

With a Master’s degree in Computer Science, he has a strong foundation in Software Engineering and a passion for robotics with Raspberry Pi.