Running Multiple Linux Commands Simultaneously

ByContributor

Understanding how to execute multiple commands at once in Linux can significantly improve your efficiency and productivity. This article will guide you through various ways you can run multiple Linux commands in a single line and even how to automate repetitive tasks.

Understanding the Basics

Before delving into advanced techniques, you should familiarize yourself with the command line or Terminal, Linux’s powerful tool. Here, you can perform tasks by typing a sequence of commands. While it may seem daunting at first, learning to use it can open up a new world of efficiency and productivity.

Running Commands Consecutively

If you want to run multiple commands consecutively, i.e., run the next command after the previous one finishes, use the semicolon (;). For instance, command1 ; command2 ; command3 will execute command1, wait for it to finish, and then execute command2 and so on.

Executing Commands in Parallel

To run commands simultaneously or in parallel, use the ampersand (&). However, keep in mind that using an ampersand sends the process to the background, allowing the next command to start immediately. For instance, command1 & command2 executes both command1 and command2 at the same time.

Using the Logical Operators

You can also employ logical operators (&& and ||) to run commands based on the success or failure of the previous command. The ‘&&’ operator will execute the next command if the previous one succeeds. For instance, command1 && command2 will only execute command2 if command1 is successful. Conversely, the ‘||’ operator will execute the next command only if the previous one fails.

Grouping Commands

If you have a group of commands that you want to execute in a specific order, you can use parentheses. For example, (command1 ; command2) & command3 will run command1 and command2 simultaneously but will only initiate command3 once both have completed.

Utilizing Command Line Pipes

Pipes are an invaluable tool when you want to pass the output of one command as the input to another. You can do this by using the vertical bar (|). For instance, command1 | command2 would pass the output of command1 as input to command2.

Automating Repetitive Tasks

If you frequently execute a particular set of commands, you can write a simple bash script to automate the process. All you have to do is write the commands in a text file and save it with a .sh extension. For example, you can create a file named ‘myscript.sh’ and write:

#!/bin/bash command1 command2 command3

Then, run chmod +x myscript.sh to make the script executable and execute it with ./myscript.sh.

In Conclusion

Mastering the art of executing multiple Linux commands at once can be a real time-saver and greatly enhance your workflow. By understanding the semicolon, ampersand, logical operators, parentheses, pipes, and bash scripting, you’ll have the ability to make the terminal work for you in more efficient and powerful ways.

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The Linux command line interface provides a wealth of tools for text processing, and one of the most powerful among them is the sed command. Sed, an abbreviation for Stream EDitor, is a versatile tool that allows for complex manipulation of text files and streams​​.

What is Sed?

Sed is a non-interactive text editor that operates on piped input or text files. By providing it with instructions, you can make it modify and process text in files or streams. The most common use cases of sed include operations like selecting text, substituting text, modifying an original file, adding lines to text, or deleting lines from the text. It can be used from the command line in Bash and other command-line shells​.

Sed Command Syntax

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  1. Options: These control the output of the command.
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Sed Vs. Awk

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  • Awk, on the other hand, is a tool for text processing and writing potent programs in the form of statements. It’s complex, versatile, and more powerful than sed, but also more complicated to use​​.

Exploring Sed with Examples

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Substituting Text

One of the most common operations in sed is text substitution. This is done using the s command. For example, to replace the first instance of a pattern abc with another pattern def, use:

sed s/abc/def/ ik.txt

Here, only the first instance of abc in each line is substituted with def. If you want to replace the third instance of a pattern, you can use:

sed s/abc/z/3 ik.txt

Global Substitutions

In a global substitution, all instances of a pattern are replaced. This is achieved by appending g to the substitute command. To replace all instances of abc with XYZ, use:

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