Methods to Run Multiple Commands on Linux at Once

Introduction

Before we begin talking about different methods to run multiple commands on Linux at once, let's briefly understand – What is Linux terminal?

The Linux terminal is an effective tool that enables you to use commands to carry out numerous system-wide operations. You can efficiently perform a number of tasks with shell commands, including managing programmes, automating services, and manipulating files.

However, performing commands one at a time is inefficient when carrying out several actions. It is faster to chain numerous commands in one line. This not only expedites the procedure, but also saves you time.

In this tutorial, you will run multiple commands on Linux at once. We will also address a few FAQs on methods to run multiple commands on Linux at once.

Running Multiple Linux Commands at Once

Three operators are used by Linux to enable you to run multiple commands in a single line:

• The Semicolon (;) operator
• The Logical OR (||) operator
• The Logical AND (&&) operator

These operators can all execute two or more shell commands simultaneously. However, you may create commands more effectively by being aware of which operator to use and when. The purpose and the syntax for correctly using these operators are covered in the following sections:

1. Using the Semicolon (;) Operator

The most typical method for running numerous commands in a Linux terminal is to separate each command in a chain with a semicolon. This is partly because of how the operator works, which executes each command in the sequence, whether the one before it executed correctly.

For instance, using the semicolon operator between two commands: command A and command B ensures that both commands are run consecutively, regardless of the output of the first command.

command A ; command B

The semicolon operator is the way to go if you need to simultaneously execute two or more unrelated terminal commands, such that the output status of the first command doesn't affect the execution of the latter.

Example use case: You can use the following commands to view the hostname of the system and the name of the current user:

whoami ; hostname

Remember that the shell runs these commands in the exact sequence that you listed them. The output would seem as follows:

2. Using the OR (||) Operator

When you run two commands using the OR operator, you instruct the shell to execute only one command out of the two, which is obvious from the definition of the word "or" in this context.

Consider the following scenario: you've used the OR operator with two commands: command A and command B. With the OR operator, the conjoined command would appear as follows:

command A || command B

Here, command B will only run if command A is unsuccessful, that is, if command A returns an error. Similarly, if command A is successful, command B will not be carried out.

When you need to run two related tasks simultaneously so that the shell only performs the subsequent command when the previous one fails, you can use the OR operator.

Example use case: Suppose you want to make a new file called Document.txt, but you want to make sure it doesn't already exist in the current directory before you make it. In this case, you can execute your commands in the following order:

find . Document.txt || touch Document.txt

The find command will now search for the Documents.txt file in the current working directory. If it locates the file, the chain of commands will stop and the second command won't be executed.

The command to the right will be executed and a new file with the name Document.txt will be created in your current working directory if, on the other hand, it is unable to locate the file.

3. Using the AND (&&) Operator

The AND operator, as you might have guessed, enables you to run several commands consecutively; that is, it only executes the next command in a sequence when the previous operation has successfully completed.

To better appreciate this, imagine a situation where you want to execute two related commands, but you only want the second command to execute if the first one produces a legitimate output. In this situation, you can combine the commands by using the AND operator, abbreviated as &&, to achieve the desired outcome.

Example use case: Making a new directory and entering it right away is one of the most frequent uses of the AND operator on Linux. This will save you from having to execute the two commands separately to complete the task.

Let's assume for the purpose of this tutorial that you want to instantaneously switch from your current working directory to a new one called Documents. Here's how to go about it:

mkdir Documents && cd Documents

The mkdir command will now create a new directory in your current working directory called Documents. If it is successful, the cd command will be able to run.

Combining Multiple Operators to Meet Your Execution Criteria

You can group numerous operators in your commands in addition to utilizing them individually to meet your execution requirements. When you wish to run commands that fulfil many conditions, this is useful.

For example, imagine a situation where you only wish to run commands B and C when command A fails. You'll need to employ the operators as shown in the following notation to accomplish this:

command A || command B && command C

Example use case: Consider the case where you wish to check to see if a folder (called Document) already exists in your current working directory, and create it if it does not.

In this situation, you can utilize the OR and AND operators together to efficiently complete the process, rather than running separate commands to locate the directory and create a new one.

It would seem as follows:

find . Document || echo "Directory not found" && mkdir Document

find instructs the shell to look in the current working directory for a folder named Document. If the directory isn't found, the terminal switches to the echo and mkdir commands, which print the provided string and create a new folder, respectively.

Running Multiple Commands at Once Using Shell Scripts

A shell script is a piece of software that enables you to automatically run several commands at once. It saves time and effort by removing the need to type numerous commands into the Linux terminal.

Simply compile all the frequently used commands into a script and save it as an executable file. Then, simply run it whenever you need to run those commands, and it will take care of everything.

Create a new file first, then enter all the commands you wish to run at once in it. Include a ".sh" extension at the end after saving the file with the proper name.

Go to the folder where you saved the script in the terminal after opening it. To make the file executable, use the following command:

chmod +x file_name

The following time you need to run those commands again, navigate to the folder where the script file is located in the terminal, and run it as follows:

./file_name

System upgrades are one usage for which you can put this to use. You may develop a script that automatically runs the sudo apt update and sudo apt upgrade commands for you, rather than having to manually type them into the terminal each time you wish to update your system.

Simply use the following command to create a script file, then carry out the next steps as shown above:

#!/bin/bash
sudo apt update && sudo apt upgrade -y

Efficiently Running Terminal Commands on Linux

As you just saw, the majority of command-line activities can be made simpler by employing operators in your commands.

Knowing how to use these operators can be quite beneficial and help you run Linux commands more effectively if you choose to carry out various system activities on your computer through the terminal.

Similar to this, learning various terminal commands is another step towards understanding the command-line interface, whether you're just getting started with Linux or are less familiar with it.

FAQs to Run Multiple Commands on Linux at Once

Conclusion

After following the tutorial till the end, you know all the ways in which you can run multiple commands at once on Linux. If you have any queries or doubts, please leave them in the comment below. We'll be happy to address them.