rev command in Linux with Examples

rev command in Linux is used to reverse the lines characterwise. This utility reverses the order of the characters in each line by copying the specified files to the standard output. If no files are specified, then the standard input will be read.

Here, we will explore the syntax, examples, and options associated with the rev command, to effectively utilize in your Linux environment.

Syntax

rev [option] [file...]

where,

• file...: Specifies the file(s) to process. If no file is provided, rev will read from standard input.
• options: Command-line options that modify the behavior of the rev command.

Examples of Using the rev Command

Example 1: Reversing Input from Standard Input

If you want to reverse a string or input directly from the terminal, you can use the rev command without specifying a file.

In this example, the rev command reverses the characters in the string "GeeksforGeeks" and outputs the reversed text.

Example 2: Reversing the Contents of a File

Suppose we have a text file named as 'sample.txt'.

Using rev command on sample file. It will display the result on the terminal as follows:

Each line in the file is processed individually, and the characters within each line are reversed.

Common Options for the rev command

The rev command comes with a few options that can be helpful for specific tasks. Below are the available options:

1. -V (version):

This option displays the version information of the rev command and then exits

rev -V

2. -h (help):

This option prints a help message, displaying the available options and usage of the rev command.

rev -h

Conclusion

The rev command in Linux is a useful utility for reversing the order of characters in each line of text, whether it's from a file or direct input. While the command is simple, it can be powerful when combined with other Linux commands for text manipulation tasks. By understanding its syntax, options, and examples, you can incorporate rev into your Linux workflow to simplify text processing tasks.