Linux rev Command with Practical Examples

Introduction

In this lab, you will learn how to use the Linux rev command, which is a versatile utility for reversing the order of characters or lines in text files. The lab covers understanding the basic functionality of the rev command, as well as practical examples of reversing text within files and reversing the order of lines. This lab provides a useful introduction to this miscellaneous Linux utility, which can be employed in various text processing scenarios.

Linux Commands Cheat Sheet

Skills Graph

Understand the rev Command

In this step, you will learn about the rev command in Linux, which is used to reverse the order of characters in each line of a file.

The rev command reads the specified files line by line, and writes each line to the standard output with the characters in reverse order. If no files are specified, rev reads from the standard input.

Let's start by running the rev command on a simple text file:

echo "Hello, World!" > example.txt
rev example.txt

Example output:

!dlroW ,olleH

As you can see, the rev command has reversed the order of characters in the line.

You can also use rev to reverse the order of lines in a file:

cat <<EOF > example.txt
Line 1
Line 2
Line 3
EOF
rev example.txt

Example output:

3 eniL
2 eniL
1 eniL

In this example, the rev command has reversed the order of the lines in the example.txt file.

The rev command is a simple but useful utility in the Linux command-line toolkit. It can be used in various scenarios, such as reversing text for obfuscation, or as part of more complex text processing pipelines.

Reverse Text in Files

In this step, you will learn how to use the rev command to reverse the text within files.

Let's start by creating a sample text file:

cat << EOF > example.txt
This is a sample text file.
The quick brown fox jumps over the lazy dog.
EOF

Now, let's use the rev command to reverse the text in the file:

rev example.txt

Example output:

.elif txet elpmas a si sihT
.god yzal eht revo spmuj xof nworb kciuq ehT

As you can see, the rev command has reversed the order of characters in each line of the file.

You can also combine the rev command with other commands to perform more complex text manipulations. For example, to reverse the text and save the result to a new file:

rev example.txt > reversed_example.txt
cat reversed_example.txt

Example output:

.elif txet elpmas a si sihT
.god yzal eht revo spmuj xof nworb kciuq ehT

In this example, we used the rev command to reverse the text in the example.txt file, and then redirected the output to a new file called reversed_example.txt.

The rev command is a simple but powerful tool for manipulating text in Linux. It can be used in various scenarios, such as obfuscating sensitive information, or as part of more complex text processing pipelines.

Reverse Lines in Files

In this step, you will learn how to use the rev command to reverse the order of lines in a file.

Let's start by creating a sample text file with multiple lines:

cat << EOF > example.txt
Line 1
Line 2
Line 3
Line 4
Line 5
EOF

Now, let's use the rev command to reverse the order of the lines in the file:

rev example.txt

Example output:

5 eniL
4 eniL
3 eniL
2 eniL
1 eniL

As you can see, the rev command has reversed the order of the lines in the example.txt file.

You can also combine the rev command with other commands to perform more complex line manipulations. For example, to reverse the lines and save the result to a new file:

rev example.txt > reversed_example.txt
cat reversed_example.txt

Example output:

5 eniL
4 eniL
3 eniL
2 eniL
1 eniL

In this example, we used the rev command to reverse the lines in the example.txt file, and then redirected the output to a new file called reversed_example.txt.

The rev command is a simple but powerful tool for manipulating lines in text files. It can be used in various scenarios, such as rearranging the order of lines in a configuration file, or as part of more complex text processing pipelines.

Summary

In this lab, you learned how to use the rev command in Linux to reverse the order of characters in each line of a file, as well as the order of lines within a file. You explored practical examples of reversing text in files and discovered how the rev command can be combined with other commands for more complex text manipulations. The key learning points covered in this lab include understanding the basic functionality of the rev command, reversing text within files, and reversing the order of lines in files.

Linux Commands Cheat Sheet