Sequence command in linux

Seq Command in Linux

Print a sequence of numbers with specified increment or format with seq command.

The seq command, short for sequence, is used for printing a sequence of numbers. The numbers could be integers or real (with decimal points).

Let’s see how you can use this command with some examples.

Using seq command

You can use seq without options for producing sequence of numbers in 3 different formats.

Print sequence of numbers till an upper limit

In the simplest form, you specify an upper limit to seq and it will print the sequence beginning from 1 till the upper limit.

Print sequence between two numbers (lower and upper limit)

You can provide two numbers in ascending order and it will print the sequence starting from the lower number till the upper one.

Have a look at this example:

Print sequence between a limit but with custom increment

So far, the increment in the sequence has been one. But you may also define a custom increment between the lower and upper limit.

The incremental value can be an integer or a decimal value.

[email protected]:~$ seq 3 0.5 6 3.0 3.5 4.0 4.5 5.0 5.5 6.0 

Print a sequence backward

Another trick is to print a sequence backward. To do that, you have to specify a negative increment.

A screenshot of all the above examples:

What happens when you put something like 0.7? In that case, the upper limit will not be breached.

[email protected]:~$ seq 3 0.7 6 3.0 3.7 4.4 5.1 5.8 

So far, you have not used any options with seq command. Let’s see and use them as well.

Print sequence with same width

The option w with seq command is used to keep the same width for the printed numbers.

Print sequence in a specific format

You may format the output line in a specified format with the option f .

%g is used for default numbers. %e to display the number in exponential format and %f in floating-point format.

Print sequence with string as separator

So far, the sequence were all printed vertically. That’s because by default, the separator is the new line character. You may change that with option s .

The ‘ before the separator is not necessary but it is good for avoiding bad surprises.

Practical use of seq command

You may wonder what could be a practical use of this seq command. There could be numerous situations where you could use it.

One particular example I can think of is when you use for loop in bash. Instead of specifying the sequence manually in the loop condition, you can use the seq command.

#!/bin/bash for i in $(seq 4 2 18) do echo "Number $i" done

When you run the above bash script, it will loop on the given sequence and print the values.

[email protected]:~$ bash seq.sh Number 4 Number 6 Number 8 Number 10 Number 12 Number 14 Number 16 Number 18

That’s pretty much all the important stuff you need to know about the seq command. If you want more details, you can always use its man page.

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The Seq Linux Command With Examples

The seq Linux command generates numbers from a specified starting number to the specified last number. The command works like conditional statements, such as while and for loops.

You can use the seq command to iterate a sequence of numbers on the command line or even in Bash. You can also pipe the output to the other files or programs. We will cover all that in this article.

Working with Seq Command

The seq command comes preinstalled on Linux. Its basic syntax is:

The seq command generates a sequence of numbers. You can define how to generate the numbers.1

1. Working with Seq LAST

When only one argument is given, seq treats it as the LAST. It prints the numbers starting from 1 and increments up to that number. The default increment is by 1.

For instance, to use 14 as our argument, the output will be:

2. Working with Seq FIRST and LAST

You can specify where to start the sequence number by adding two arguments. The first represents the starting value, and the other is the last value to be printed. However, the first argument can’t be greater than the LAST argument.

Let’s print the sequence starting from 3 to 14. The command will be:

3. Working with Seq FIRST INCREMENT LAST

When seq receives three arguments, it treats the first argument as the starting point when the sequence number starts. The second argument is the increment number, and the third argument is the last number.

For instance, to print 3 to 14, incrementing the value by 2, the command will be:

4. Working with Formatted Strings

Seq allows the concatenating strings with sequence numbers using the” %g” option. The string format is similar to the C programming, and you can specify the number of characters. Let’s see some of the few examples.

To add the strings before the sequence number, apply the following command:

The previous command prints the sequence numbers from 1 to 5 and appends the words and zeros before the number.

You can also specify an increment and the starting value.

For instance, to print the same formatted strings starting from 11 and incrementing by 4 up to 25, the command will be:

The output would be as follows:

Seq prints the output each on its line. If you prefer displaying the result on the same line, use the -s flag.

5. Working with Seq -w

By default, the width padding of the output is not equal, especially when working with numbers that don’t have the same number of digits. However, you can append the leading zeros to equalize the width using the -w.

6. Working with Separators

A separator is needed when generating the sequence numbers, especially on the same line. The seq offers the -s flag that lets you define the type of separator to use. We added different separators in the following example:

7. Working with Floating-Point Numbers

When you need to generate a sequence containing the floating values, use the “%f” option and add an increment value. For instance, to add a 0.5 increment, the command will be:

8. Working with Bash Scripts Using Seq

You can use the seq in creating Bash scripts. In our case, we will create a Bash script that generates the sequence numbers from 2 to 10 with a 0.8 increment.

The code for the script will be:

Make the script executable and run it to generate the output.

You can also create a script that creates files starting with a given keyword followed by the generated numbers. In our case, we create a script that creates files named lecture and uses the seq to name them.

Run the script. Note the output and how it creates the different files, as shown in the following:

You can also create multiple files on the terminal without using a script. To make the same files as we did, using the Bash script, but on the terminal instead, the command will be:

9. Piping the Seq Output to a File

You can save the output of the sequence number to a new file using the different options. In our case, we will pipe the output to a new file that gets created when the command runs.

Conclusion

Seq is a prompt Linux command that instantly generates the needed sequence numbers. You’ve now understood how to use the seq to create the sequence numbers in different ways, including using it with Bash scripts. You will enjoy how quick it gets the job done.

About the author

Denis Kariuki

Denis is a Computer Scientist with a passion for Networking and Cyber Security. I love the terminal, and using Linux is a hobby. I am passionate about sharing tips and ideas about Linux and computing.

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Linux Tutorial: Understanding The Seq Linux Command With Examples

Are you looking to learn more about the Seq Linux command? If so, this Linux tutorial is perfect for you. In this article, you’ll gain an in-depth understanding of the Seq command and how to use it with examples. By the end of this article, you’ll be able to use the Seq command to its fullest potential. So, if you want to get the most out of Linux, read on!

The Seq Linux command is a powerful tool for performing various operations on text files. It allows users to search, compare, and modify text files quickly and easily. It’s a great tool for working with text-based files like scripts, configuration files, and more. Seq is an incredibly useful command and can save you a lot of time when working with text-based files.

In order to use the Seq command properly, you’ll need to understand the syntax and options available. This tutorial will provide you with an in-depth overview of the Seq command and its various options and parameters. We’ll also provide examples of how to use the Seq command to search and modify text files. By the end of this tutorial, you’ll be able to use the Seq command confidently and effectively.

So, let’s get started and learn more about the Seq Linux command! Whether you’re a novice or experienced Linux user, this tutorial will provide you with a comprehensive understanding of the Seq command and how to use it. Read on and get ready to master the Seq command!

Understanding the Seq Linux Command with Examples

to the Seq Command

The seq command is a Linux utility that is used to generate and print a sequence of numbers. It can be used to print a range of numbers and also generate a list of numbers in a particular order. The seq command is often used in scripting and programming to generate a series of numbers. It is especially useful when needing to create a loop in a script. It is also useful when performing data analysis or other types of operations that involve using a sequence of numbers.

Using the Seq Command

The basic syntax of the seq command is “seq [OPTION]… FIRST INCREMENT LAST”. The FIRST argument specifies the starting point for the sequence, the INCREMENT argument is the amount to increment the sequence each time, and the LAST argument specifies the ending point for the sequence. Here’s an example of how the seq command can be used to generate a sequence of numbers from 1 to 10, incrementing by 1 each time:

Using the Seq Command with Options

The seq command can also be used with various options to customize the sequence of numbers it generates. For example, the “-f” option can be used to format the output, while the “-s” option can be used to specify a custom separator. Here’s an example of using the “-f” and “-s” options to generate a sequence of numbers from 1 to 10, incrementing by 1 each time, with a custom format and separator:

$ seq -f Number %g -s , 1 1 10Number 1,Number 2,Number 3,Number 4,Number 5,Number 6,Number 7,Number 8,Number 9,Number 10

Using the Seq Command for Loops

The seq command can be used to generate sequences of numbers in a loop. This can be especially useful in bash scripts, as it allows for the script to loop through a range of numbers. Here’s an example of using the seq command in a loop to generate a sequence of numbers from 1 to 10, incrementing by 2 each time:

for i in $(seq 1 2 10); do echo $idone13579

Using the Seq Command to Generate Random Numbers

The seq command can also be used to generate random numbers. This can be done by using the “-r” option, which reverses the sequence of numbers. Here’s an example of using the “-r” option to generate a random sequence of numbers from 1 to 10, incrementing by 1 each time:

In this tutorial, we have learned how to use the seq command to generate and print a sequence of numbers. We have seen how to use the seq command with different options to customize the output and how to use it in a loop to generate a range of numbers. We have also seen how to use the “-r” option to generate a random sequence of numbers. The seq command is a powerful and useful tool for scripting and programming in Linux.

Suggestions to Improve Coding Skill

To improve coding skills related to the seq command, it is important to practice writing scripts that use it. Try writing scripts that use the seq command to generate sequences of numbers, output formatted sequences, and generate random sequences. Additionally, it is important to become familiar with the various command line options available for the seq command, as they can be useful in certain situations. Finally, it is important to understand how the seq command can be used in a loop, as this can be a powerful tool for programming in Linux.

Video How to use the sequence command: 2-Minute Linux Tips

Source: CHANNET YOUTUBE IDG TECHtalk

Understanding the Seq Linux Command with Examples

What is the Seq Linux command?

Seq is a command line tool for viewing and manipulating sequences. It can be used to view, analyze, and transform sequences from a variety of sources, including text files, databases, and the web.

What are some examples of Seq commands?

• seq -f Sequence %g: %s my_sequence.txt
• seq -i Sequence %g: %s my_sequence.txt
• seq -p Sequence %g: %s my_sequence.txt
• seq -s my_sequence.txt

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