less command in Linux with Examples

Last Updated : 08 Sep, 2024

The ‘less’ command in Linux is an indispensable utility for browsing the contents of text files interactively. Unlike traditional text editors, ‘less’ allows you to view text files page by page without loading the entire file into memory. This approach not only speeds up the file loading process, especially for large files, but also enhances your ability to manage and review lengthy documents or logs efficiently.

What is the ‘less’ command?

At its core, the ‘less’ command operates as a powerful pager program, optimized for quick and resource-efficient viewing of text data. ‘less’ provides a pragmatic solution for exploring and searching text without the overhead of file editors like vi or nano.

Syntax:

The basic syntax of the less command is as follows:

less [options] filename

Here, `filename` represents the name of the file we want to view using the `less` command.

Using ‘less’ with Pipelines

The less command can also be used in conjunction with other commands through pipelines. This allows us to view the output of a command directly in the less pager.

Note: I’m using dmesg output as input to less command in the following examples.

For Example: If you want to read the contents of dmesg command, it’s better to use it with fewer command

dmesg | less

Output:

Commonly Used Options in`less`command

The less command provides several options that modify its behavior. Here are some commonly used options:

Options	Description
-E	Automatically exit when reaching the end of the file.
-f	Force non-regular files to be opened.
-F	Exit if the entire file can be displayed on the first screen.
-g	Highlight the string that was found by the last search command.
-G	Suppress highlighting of search matches.
-i	Ignore cases when searching.
-n	Suppress line numbers.
-p pattern	Start at the first occurrence of the specified pattern in the file.
-s	Squeeze consecutive blank lines into a single line.

We can combine these options to customize the behavior of the less command according to our needs.

Examples of `less` command in Linux

Let’s look at a few examples to illustrate the usage of the less command with different options.

1. Searching for a pattern

dmesg | less -p "fail"

The above command tells less to start at first occurrence of pattern “fail” in the file and displaying the file from that point.

Output:

2. Displaying line number

dmesg | less -N

The -N option displays line numbers along with the file content, allowing you to reference specific lines easily.

Output:

3. Checking a small file

less -F /home/Mandeep/test/first.erl

In this example, the file `/home//Mandeep/test/first.erl` is small enough to fit on a single screen. The `-F` option causes less to exit immediately without displaying the file since it can be fully shown in one go.

Conclusion

In this article we have discussed `less` command which allows users to read large text files efficiently by loading and displaying them incrementally. We can say that by utilizing less with pipelines, users can also directly view the output of other commands, enhancing its usefulness. Overall, less command is a valuable tool for managing and exploring the contents of text files in Linux.