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How to Use Grep and Regular Expressions in Linux

How to Use Grep and Regular Expressions in Linux
Hostman Team
Technical writer
Linux
11.02.2025
Reading time: 16 min
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GREP (short for "global regular expression print") is one of the most popular utilities in the Linux operating system.

With it, you can search for phrases (sequences of characters) in multiple files simultaneously using regular expressions and filter the output of other commands, keeping only the necessary information.

This guide will cover how to search for specific expressions in a set of text files with various contents using the GREP utility.

All examples shown were run on a cloud server hosted by Hostman running Ubuntu version 22.04.

How Does GREP Work

The GREP command follows this structure:

grep [OPTIONS] [PATTERN] [SOURCES]

Where:

  • OPTIONS: Special parameters (flags) that activate certain mechanisms in the utility related to searching for expressions and displaying results.

  • PATTERN: A regular expression (or plain string) containing the phrase (pattern, template, sequence of characters) you want to find.

  • SOURCES: The path to the files where we will search for the specified expression.

If the GREP command is used to filter the output of another command, its structure looks a bit different:

[COMMAND] | grep [OPTIONS] [PATTERN]

Thus:

  • COMMAND: An arbitrary command with its own set of parameters whose output needs to be filtered.

  • The "pipe" symbol (|) is necessary to create a command pipeline, redirecting streams so that the output of an arbitrary command becomes the input for the GREP command.

Preparation

To understand the nuances of using GREP, it's best to start with small examples of searching for specific phrases. Therefore, we will first create a few text files and then test the GREP command on them.

Let’s first prepare a separate directory where the search will take place:

mkdir texts

Next, create the first file:

nano texts/poem

It will contain one of Langston Hughes's poems:

Hold fast to dreams  
For if dreams die  
Life is a broken-winged bird  
That cannot fly.  
Hold fast to dreams  
For when dreams go  
Life is a barren field  
Frozen with snow.

Now, create the second file:

nano texts/code.py

It will contain a simple Python script:

from datetime import date

dateNow = date.today()
print("Current time:", dateNow)

Finally, create the third file:

nano texts/page.html

This one will have simple HTML markup:

<html>
	<head>
		<title>Some Title</title>
	</head>

	<body>
		<div class="block">
			<p>There's gold here</p>
		</div>

		<div class="block">
			<p>A mixture of wax and clouds</p>
		</div>

		<div class="block block_special">
			<p>Today there's nothing</p>
		</div>
	</body>
</html>

By using files of different formats, we can better understand what the GREP command does by utilizing the full range of the utility's features.

Regular Expressions

Regular expressions are the foundation of the GREP command. Unlike a regular string, regular expressions contain special characters that allow you to specify phrases with a certain degree of variability.

When using the GREP utility, regular expressions are placed within single quotes:

'^date[[:alpha:]]*'

Thus, the full command can look like this:

grep '^date[[:alpha:]]*' texts/*

In this case, the console output will be:

texts/code.py:dateNow = date.today()

However, using double quotes allows you to pass various system data into the expression. For example, you can first create an environment variable with the search expression:

PATTERN="^date[[:alpha:]]*"

And then use it in the GREP command:

grep "$PATTERN" ./texts/*

Additionally, using single backticks allows you to use bash subprocess commands within the GREP command. For example, you can extract a regular expression from a pre-prepared file:

grep `cat somefile` ./texts/*

Note that with the asterisk symbol (wildcard), you can specify all the files in the directory at once. However, the GREP command also allows you to specify just one file: 

grep '^date[[:alpha:]]' texts/code.py 

Because regular expressions are a universal language used in many operating systems and programming languages, their study is a separate vast topic. 

However, it makes sense to briefly cover the main special characters and their functions. It’s important to note that regular expressions in Linux can work in two modes: basic (Basic Regular Expression, BRE) and extended (Extended Regular Expression, ERE). The extended mode is activated with the additional flag -E. The difference between the two modes lies in the number of available special characters and, consequently, the breadth of available functionality.

Basic Syntax

Basic syntax allows you to define only general formal constructs without considering the specific configuration of their characters.

Start of a line — ^

The caret symbol indicates that the sought sequence of characters must be at the beginning of the line:

grep '^Hold' texts/*

The console output will be as follows:

texts/poem:Hold fast to dreams
texts/poem:Hold fast to dreams

End of a line — $

The dollar sign indicates that the sought sequence of characters must be at the end of the line:

grep '</p>$' texts/*

Output:

texts/page.html:                        <p>There's gold here</p>
texts/page.html:                        <p>A mixture of wax and clouds</p>
texts/page.html:                        <p>Today there's nothing</p>

Note that the console output preserves the original representation of the found lines as they appear in the files.

Start of a word — \<

The backslash and less-than symbol indicate that the sought phrase must be at the beginning of a word:

grep '\<br' texts/*

Output:

texts/poem:Life is a broken-winged bird

End of a word — \>

The backslash and greater-than symbol indicate that the sought sequence of characters must be at the end of a word:

grep 'en\>' texts/*

Output:

texts/poem:Life is a broken-winged bird
texts/poem:For when dreams go
texts/poem:Life is a barren field
texts/poem:Frozen with snow.

Start or end of a word — \b

You can specify the start or end of a word using the more universal sequence of characters — backslash and the letter b.

For example, this marks the beginning:

grep '\bdie' texts/*

Output:

texts/poem:For if dreams die

And this marks the end:

grep '<div\b' texts/*

In this case, the console terminal output will be as follows:

texts/page.html:                <div class="block">
texts/page.html:                <div class="block">
texts/page.html:                <div class="block block_special">

Any character — .

Certain characters in the sought phrases can be left unspecified using the dot symbol:

grep '..ere' texts/*

Output:

texts/page.html:                        <p>There's gold here</p>
texts/page.html:                        <p>Today there's nothing</p>

Extended Syntax

Unlike basic syntax, extended syntax allows you to specify the exact number of characters in the sought phrases, thus expanding the range of possible matches.

Combining patterns — |

To avoid running the GREP command multiple times, you can specify several patterns in a single regular expression:

grep -E '^Hold|</p>$' texts/*

The result of running this command will be a combined console output containing the search results for the two separate regular expressions shown earlier.

texts/page.html:                        <p>There's gold here</p>
texts/page.html:                        <p>A mixture of wax and clouds</p>
texts/page.html:                        <p>Today there's nothing</p>
texts/poem:Hold fast to dreams
texts/poem:Hold fast to dreams

Repetition range — {n, d}

In some cases, certain characters in the sought phrase may vary in quantity. Therefore, in the regular expression, you can specify a range of the allowed number of specific characters.

grep -E 'en{1,2}' texts/*

Output:

texts/code.py:print("Current time:", dateNow)
texts/poem:Life is a broken-winged bird
texts/poem:For when dreams go
texts/poem:Life is a barren field
texts/poem:Frozen with snow.

However, frequently used repetition intervals are more conveniently written as special characters, thus simplifying the appearance of the regular expression.

One or more repetitions — +

A repetition interval from one to infinity can be expressed using the plus sign:

grep -E 'en+' texts/*

In this case, the console output will not differ from the previous example.

texts/code.py:print("Current time:", dateNow)
texts/poem:Life is a broken-winged bird
texts/poem:For when dreams go
texts/poem:Life is a barren field
texts/poem:Frozen with snow.

Zero or one repetition — ?

A repetition interval from 0 to 1 can be expressed using the question mark:

grep -E 'ss?' texts/*

As a result, this command will produce the following output in the console terminal:

texts/page.html:                <div class="block">
texts/page.html:                        <p>There's gold here</p>
texts/page.html:                <div class="block">
texts/page.html:                        <p>A mixture of wax and clouds</p>
texts/page.html:                <div class="block block_special">
texts/page.html:                        <p>Today there's nothing</p>
texts/poem:Hold fast to dreams
texts/poem:For if dreams die
texts/poem:Life is a broken-winged bird
texts/poem:Hold fast to dreams
texts/poem:For when dreams go
texts/poem:Life is a barren field
texts/poem:Frozen with snow.

Character set — [abc]

Instead of one specific character, you can specify an entire set enclosed in square brackets:

grep -E '[Hh]o[Ll]' texts/*

Output:

texts/poem:Hold fast to dreams
texts/poem:Hold fast to dreams

Character range — [a-z]

We can replace a large set of allowed characters with a range written using a hyphen:

grep -E 'h[a-z]+' texts/*

Output:

texts/page.html:<html>
texts/page.html:        <head>
texts/page.html:        </head>
texts/page.html:                        <p>There's gold here</p>
texts/page.html:                        <p>Today there's nothing</p>
texts/page.html:</html>
texts/poem:That cannot fly.
texts/poem:For when dreams go

Moreover, character sets and ranges can be combined:

grep -E 'h[abcd-z]+' texts/*

Each range is implicitly transformed into a set of characters:

  • [a-e] into [abcde]
  • [0-6] into [0123456]
  • [a-eA-F] into [abcdeABCDEF]
  • [A-Fa-e] into [ABCDEFabcde]
  • [A-Fa-e0-9] into [ABCDEFabcde0123456789]
  • [a-dA-CE-G] into [abcdABCEFG]
  • [acegi-l5-9] into [acegijkl56789]

Character type — [:alpha:]

Frequently used ranges can be replaced with predefined character types, whose names are specified in square brackets with colons:

[:lower:]

characters from a to z in lowercase

[:upper:]

characters from A to Z in uppercase

[:alpha:]

all alphabetic characters

[:digit:]

all digit characters

[:alnum:]

all alphabetic characters and digits

It is important to understand that the character type is a separate syntactic construct. This means that it must be enclosed in square brackets, which denote a set or range of characters:

grep -E '[[:alpha:]]+ere' texts/*

Output:

texts/page.html:                        <p>There's gold here</p>
texts/page.html:                        <p>Today there's nothing</p>

Filtering Output

To filter the output of another command, you need to write a pipe symbol after it, followed by the standard call to the GREP utility, but without specifying the files to search:

cat texts/code.py | grep 'import'

Like when searching in regular files, the console output will contain the lines with the matches of the specified phrases:

from datetime import date

In this case, the cat command extracts the file content and passes it to the input stream of the GREP utility.

Search Options

In addition to regular expressions, you can specify additional keys for the GREP command, which are special options in flag format that refine the search.

Extended Regular Expressions (-E)

Activates the extended regular expressions mode, allowing the use of more special characters.

Case Insensitivity (-i)

Performs a search for a regular expression without considering the case of characters:

grep -E -i 'b[ar]' texts/*

The console output corresponding to this command will be:

texts/poem:Life is a broken-winged bird
texts/poem:Life is a barren field

You can also specify flags together in a single string:

grep -Ei 'b[ar]' texts/*

Whole Word (-w)

Performs a search so that the specified regular expression is a complete word (not just a substring) in the found line:

grep -w and texts/*

Note that quotes are not required when specifying a regular string without special characters.

The result of this command will be:

texts/page.html: <p>A mixture of wax and clouds</p>

Multiple Expressions (-e)

To avoid running the command multiple times, you can specify several expressions at once:

grep -e 'Hold' -e 'html' texts/*

The result of this command will be identical to this one:

grep -E 'Hold|html' texts/*

In both cases, the console terminal will display the following output:

texts/page.html:<html>
texts/page.html:</html>
texts/poem:Hold fast to dreams
texts/poem:Hold fast to dreams

Recursive Search (-r)

Performs a recursive search in the specified directory to the maximum depth of nesting:

grep -r '[Ff]ilesystem' /root

The console terminal will display output containing file paths at different nesting levels relative to the specified directory:

/root/parser/parser/settings.py:#HTTPCACHE_STORAGE = "scrapy.extensions.httpcache.FilesystemCacheStorage"
/root/resize.log:Resizing the filesystem on /dev/vda1 to 3931904 (4k) blocks.
/root/resize.log:The filesystem on /dev/vda1 is now 3931904 (4k) blocks long.

Search for Special Characters (-F)

Allows the use of special characters as the characters of the search phrase:

grep -F '[' texts/*

Without this flag, you would encounter an error in the console terminal:

grep: Invalid regular expression

An alternative to this flag would be using the escape character in the form of a backslash (\):

grep '\[' texts/*

Including Files (--include)

Allows limiting the search to the specified files only:

grep --include='*.py' 'date' texts/*

The console output will be:

texts/code.py:from datetime import date
texts/code.py:dateNow = date.today()
texts/code.py:print("Current time:", dateNow)

We can also write this command without the wildcard by using an additional recursive search flag:

grep -r --include='*.py' 'date' texts

Excluding Files (--exclude)

Selectively excludes certain files from the list of search sources:

grep --exclude='*.py' 'th' texts/*

The console output will be:

texts/page.html: <p>Today there's nothing</p>
texts/poem:Frozen with snow.

Output Options

Some parameters of the GREP command affect only the output of search results, improving their informativeness and clarity.

Line Numbers (-n)

To increase the informativeness of the GREP results, you can add the line numbers where the search phrases were found:

grep -n '</p>$' texts/*

Each line in the output will be supplemented with the corresponding line number:

texts/page.html:8:                      <p>There's gold here</p>
texts/page.html:12:                     <p>A mixture of wax and clouds</p>
texts/page.html:16:                     <p>Today there's nothing</p>

Lines Before (-B)

Displays a specified number of lines before the lines with found matches:

grep -B3 'mix' texts/*

After the flag, you specify the number of previous lines to be displayed in the console terminal:

texts/page.html-                </div>
texts/page.html-
texts/page.html-                <div class="block">
texts/page.html:                        <p>A mixture of wax and clouds</p>

Lines After (-A)

Displays a specified number of lines after the lines with found matches:

grep -A3 'mix' texts/*

After the flag, you specify the number of subsequent lines to be displayed in the console terminal:

texts/page.html:                        <p>A mixture of wax and clouds</p>
texts/page.html-                </div>
texts/page.html-
texts/page.html-                <div class="block block_special">

Lines Before and After (-C)

Displays a specified number of lines both before and after the lines with found matches:

grep -C3 'mix' texts/*

After the flag, you specify the number of preceding and following lines to be displayed in the console terminal:

texts/page.html-                </div>
texts/page.html-
texts/page.html-                <div class="block">
texts/page.html:                        <p>A mixture of wax and clouds</p>
texts/page.html-                </div>
texts/page.html-
texts/page.html-                <div class="block block_special">

Line Count (-c)

Instead of listing the found lines, the GREP command will output only the number of matches:

grep -c 't' texts/*

The console output will contain the count of matches found in all specified files:

texts/code.py:3
texts/page.html:5
texts/poem:4

If only one file is specified as the source:

grep -c 't' texts/block

The console output will contain only the number:

4

File Names (-l)

This flag allows you to output only the names of the files in which matches were found:

grep -l 't' texts/*

The console output will be as follows:

texts/code.py
texts/page.html
texts/poem

Limit Output (-m)

Limits the number of lines output to the console terminal to the number specified next to the flag:

grep -m2 't' texts/*

The console output will be:

texts/code.py:from datetime import date
texts/code.py:dateNow = date.today()
texts/page.html:<html>
texts/page.html:                <title>Some Title</title>
texts/poem:Hold fast to dreams
texts/poem:That cannot fly.

As you can see, the limiting number affects not the entire output but the lines of each file.

Exact Match of Whole Line (-x)

Searches for an exact match of the entire line with no variability:

grep -x 'Life is a broken-winged bird' texts/*

The console output will be:

texts/poem:Life is a broken-winged bird

Conclusion

The GREP command in Linux is the most flexible and precise tool for searching expressions in large volumes of text data.

When using the command, you need to specify the following elements:

  • A specific set of options (flags) that configure the search and output mechanisms.
  • One or more regular expressions that describe the search phrase.
  • A list of sources (files and directories) where the search will be performed.

Additionally, the utility is used to filter the output of other commands by redirecting input and output streams.

The core of the GREP command is regular expressions. Unlike a simple string, they allow you to define a phrase with a certain degree of variability, making it match multiple similar entries.

There are two modes of operation for regular expressions:

  • Basic Mode: A limited set of special characters that allow you to formalize expressions only in general terms.
  • Extended Mode: A full set of special characters that allows you to formalize expressions with precision down to each character.

The extended mode provides complete flexibility and accuracy when working with regular expressions.

In rare cases where you only need to find matches for trivial patterns, you can limit yourself to the basic mode.

Linux
11.02.2025
Reading time: 16 min
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Example: printf "First Line\nSecond Line\nIndented\tThird Line\n" >  formatted_file.txt Run the cat command to inspect the file's content and ensure the formatting matches expectations. Append Without Overwriting: To add content to an existing file without overwriting its current data, replace > with the append operator >>: printf "Additional content here.\n" >> formatted_file.txt Using a Text Dditor You can also create new files in linux text editors. There is always at least one integrated command-line text editor in your Linux distribution. But you can choose and install a different one according to your preferences, for example, Vim, Nano, or Emacs. Each of them has its own features and advantages. Vim vim, which stands for "Vi IMproved," is a very flexible and adaptable text editor. It is well-known for its modal editing, which allows for distinct modes for various functions like text entry, navigation, and editing. It allows split windows, multiple buffers, syntax highlighting, and a large selection of plugins for extra features. To create a text file using vim, follow the steps below: Open vim, with the desired filename as an argument. Press i to switch to Insert mode. Start typing and editing the filename.txt.  To save and exit, press Esc to ensure that command mode is running. Type: wq (write and quit) and press Enter. Nano nano is ideal for short adjustments and straightforward text files because it is lightweight and requires little setup. It provides support for basic text manipulation functions, search and replace, and syntax highlighting. To create a text file using nano, follow the steps below:  Run nano with the desired filename as an argument. It will open a new buffer for editing the file filename.txt. Start typing and editing the filename.txt.  To save and exit, press Ctrl + O to write the file, confirm the filename, and then press Ctrl + X to exit Nano. Emacs emacs is a powerful and flexible text editor that supports syntax highlighting, multiple buffers, split windows, and integration with external tools and programming languages. To create a text file using emacs, follow the steps below:  Open emacs, with the desired filename as an argument. Start typing and editing the filename.txt.  To save and exit, press Ctrl + X, followed by Ctrl + S to save the file, and then Ctrl + X, followed by Ctrl + C to exit Emacs. Note: If a message states that "VIM command not found", "nano command not found" or "emacs command not found" in Linux, it typically means that the vim, nano or emacs text editor is not installed on the system, or it's not included in the PATH environment variable, which is a list of directories where the operating system looks for executable files. To resolve this, install the text editor first using the command:  apt-get install vim apt-get install nano  apt-get install emacs Gedit An intuitive text editor that supports working with plain text and has syntax highlighting for programming languages. A straightforward graphical interface makes it usable for various tasks, from quick edits to complex document preparation. Open the Gedit Application: Launch Gedit either through the applications menu or by executing the following command in the terminal: gedit example.txt Gedit will create a new file if the specified one does not exist. Input Your Text: Type or paste your desired content into the editor. Save the File: Save your work with Ctrl + S or select File > Save. If creating a new file, specify a filename and a location. Verify: Return to the terminal and confirm the file exists with the ls command or review its content with cat. Linux File Creation Recommendations Ensure you have sufficient permissions to create files in the target directory. If they are insufficient, consider working in a directory where you have full rights (or elevate privileges with sudo). Check if a file with the identical name is already present before using the > operator, as the command will overwrite existing content. To prevent data loss, opt for the append operator >>. Familiarize yourself with the printf, echo, and text editors like vim or nano. These tools will help you reduce errors when working with files in Linux, as well as boost productivity. Use printf for creating files requiring structured content, such as configuration files or scripts with precise formatting needs. Conclusion Now you have acquainted yourself with the fundamental skill of creating a file in Linux using the terminal! Using the Linux command line, several fast and efficient methods exist to create and manage text files. Apply several techniques to meet a different requirement using the touch, echo, cat, printf commands, or text editors like vim, nano, gedit, or emacs. Users can select the method that sufficiently meets their requirements, such as creating empty files, appending text, or significantly modifying material. In summary, any of these methods enable Linux users to easily and quickly handle text files straight from the command line.
01 June 2025 · 8 min to read
Linux

How to Check OS Version in Linux

The popularity of the powerful and versatile Linux operating system lies in the variety of available versions. From Ubuntu to Red Hat, from Mint to Fedora, each Linux version offers users unique features and benefits. Hostman offers a reliable managed Linux VPS. It is important to check Linux OS version for compatibility, as varied versions have different software requirements. Using an older version may not allow you to install and run the latest software updates. Some hardware components may not be supported by certain Linux versions. Knowing your OS version can help you troubleshoot any compatibility issues. Therefore, it is important to check the Linux OS version and know which one you're using.  Knowing your OS version in Linux is obligatory for security reasons. All operating systems release updates to address security vulnerabilities, and Linux is no exception. If you know your OS version, you can be sure that the necessary security updates are installed. This is especially important for businesses and organizations dealing with confidential information and requiring strong security control. Another reason for checking Linux OS version is for support purposes. Various versions differentiate by support lifecycles. They have limited time to receive updates and support from developers. Knowing your OS version gives you an idea of ​​when it needs to be updated. An unsupported Linux version can leave your system vulnerable to security threats and compatibility issues. What is a Linux Version A Linux version, commonly termed a distro or distribution, is a customized version of the Linux operating system. It comes with a tailored mix of software, desktop environments, and functionalities. These distributions are custom-made to meet the varied needs and desires of their users. This comprises everything from individual PC users to huge corporations. Linux's open-source nature and flexibility enable various people and organizations to create and modify these distributions to meet specific needs. For example: Distributions such as Ubuntu, Debian, and Linux Mint are pretty useful for beginners because they offer user-friendly interfaces, extensive documentation, and a strong community network. Advanced distributions like Arch Linux grant unparalleled customization and autonomy, ideal for users who prefer crafting their systems from the ground up. Server-oriented distributions like CentOS and Red Hat Enterprise Linux (RHEL) are engineered for reliability, security, and top-tier performance, making them perfect for enterprise environments and critical applications. Specialized distributions like Kali Linux for security testing and Tails for anonymity are designed for specific purposes. A typical Linux distribution includes the Linux kernel (which controls hardware), a package manager (for installing and updating applications), and a set of default applications. The desktop environment (like GNOME, XFCE, or KDE) can be tailored in appearance and functionality to align with user preferences. Popular Linux distributions and their versions It’s important to check the Linux OS version as the operating system offers a large selection of distributions, each with its own unique features and characteristics. Common forms include Ubuntu, Debian, Red Hat, CentOS, Fedora and Mint. Ubuntu is famous for its user-friendly interface and regular updates. Debian is known for its strict adherence to free software principles. Red Hat Enterprise Linux (RHEL) offers a stable and secure platform for businesses. CentOS provides similar features to users for free. Fedora is distinguished by its frequent updates and use of the latest software. Mint features a more traditional desktop environment. Each version differs in software, desktop environment, and support lifecycle. Each distribution has various versions or releases with different code names and updates. Ubuntu has editions such as Bionic Beaver, Cosmic Cuttlefish and Disco Dingo, while Fedora has editions such as Silverblue and Workstation. They satisfy different needs and preferences of a wide range of users. Each Linux distribution has its own unique version numbering system, because it is an open-source operating system developed and maintained by a community of developers. Therefore, each distribution has its own set of developers who make decisions about naming and numbering their releases. Users can easily determine which version they are using and what changes have been made since the last update, and developers can track their progress and plan future releases.  Typically a three-level version numbering system with numbers separated by dots is used. The first number is a major release for updates or changes to the distribution, the second number is a minor release for bug fixes, security updates, and minor feature additions, the third number is a hotfix release for minor bug fixes and updates. Ubuntu uses a version numbering system in the format 'XX.YY.ZZ', where the first number is a year, the second is a month of release, and the third number is incremented with each new release that month. The system displays the age of release and frequency of updates. Code names, such as names of animals or cities, are also used to recognize releases of Linux distributions. Fedora uses code names for its releases like 'Bordeaux' and 'Heisenbug' to make it easier for users to navigate the different versions. There are many ways to find out the version of the Linux operating system and get distribution information about it. We’ll cover the most commonly used. Read on to learn how to check OS version in Linux. How to check the Linux OS version through the 'lsb_release' command You can apply the lsb_release command to check the Linux OS version. You’ll receive detailed information about the distribution, release, and codename of your operating system. To start, open the terminal; Type the command: lsb_release -a Press Enter to view a list of information displayed in your terminal. The Distributor ID line is a name of your Linux distribution, for instance, Ubuntu, Fedora, or CentOS. The Description line is a brief description of your Linux distribution with details such as the release number and the codename of your system. The Release line is a display of the specific version of your Linux distribution, such as '18.04' for Ubuntu or a name like 'Bionic Beaver.' The Codename line is your system’s codename assigned to each version of a Linux distribution, such as 'Bionic Beaver' for Ubuntu 18.04. How to check the OS version in Linux through the 'cat /etc/os-release' command You can apply the cat /etc/os-release command to check the OS version in Linux. It will help you quickly determine your OS version and show detailed information. To start, open the terminal;  Type the command: cat /etc/os-release Press Enter to view a list of information displayed on your terminal. The ID field is the name of your Linux distribution, such as Ubuntu or CentOS. The VERSION_ID field is the specific version of that distribution, such as Ubuntu 18.04 or CentOS 7. The cat /etc/os-release command shows other useful information about your operating system, such as the name and version of the operating system kernel, the desktop environment or window manager you are using, and the OS build and release date. How to check version of OS in Linux through the 'uname -a' command You can apply the uname -a command to check the Linux OS version. It displays detailed information about your system's kernel version, architecture, processor type, hostname, and even the date and time of the last system boot. To start, open the terminal;  Type the command: uname -a Press Enter to view a list of information displayed on your terminal. The output typically includes the Linux operating system kernel version and system architecture to ensure that you download and install the correct version of the software, avoiding compatibility issues and potential bugs. The command also provides information about the last time the system booted for analyzing system performance and identifying potential problems. Other ways to check OS version in Linux The hostnamectl command This is a new way to check the Linux OS version, available on systems using systemd. It provides more detailed data than previous methods, including kernel version, architecture, and hardware platform. To get the output, open the terminal;  Type the command: hostnamectl Press Enter to view a list of information displayed on your terminal. The /etc/os-release file The /etc directory contains configuration files and scripts used by the system, including the os-release file with information about the OS version To get the output, open the terminal and enter the command: cat /etc/os-release The /etc/issue file This file with system information is used for login prompts as well as for checking the OS version in Linux. To get the output, enter the command: cat /etc/issue The name and version of the operating system are displayed here. The version file Some Linux distributions have a version file in the /etc directory with information about the distribution and version. To get the output, open the terminal and enter the command: cat /etc/version The distribution name and version number are displayed here. How to Check Linux OS Version Using GUI This operating system has several ways to check your OS version. We have already explored the common methods through the command line interface. Now let’s learn how to check the Linux OS version without command. This is where the graphical user interface (GUI) comes into play, offering a convenient way to access system information. You need to access the system settings: To start, click on the 'Activities' button on the top-left corner of the screen; Enter 'system' in the search bar; Navigate to the 'System Settings' window and click the 'Details' option to display the OS name, version, and other system information in a new window. Checking the OS version in any Linux distribution is similar and differs slightly only in names of the buttons or windows in the search bar:   In Ubuntu click on the 'Activities' button and type 'System Settings' in the search bar, then navigate to the 'Details' tab. In Fedora click on the 'Show Applications' button and type 'Settings' in the search bar, then navigate to the 'About' tab. In CentOS click on the 'Applications' button and navigate to 'System Tools' and then 'Settings', then navigate to the 'System' tab. Checking the OS Version in Linux FAQ Let's go over a few frequently asked questions about Linux OS versions. Why is it vital to check the OS version in Linux? Verifying the OS version in Linux is essential for ensuring compatibility, maintaining security, and accessing support. Each version has distinct software prerequisites, life cycle durations, and security patches. How often should I check my Linux OS version? Consistently verifying your OS version is crucial, especially before adding new software or updates. This practice keeps your system current and secure. What are some of the widely recognized Linux distributions? Some widely recognized Linux distributions are Ubuntu, Debian, Kali Linux, Raspberry Pi, CentOS, Fedora, and Linux Mint. Each one boasts unique features designed to cater to the diverse needs of its user base. Can I check the Linux OS version using a GUI? Yes, you can check the Linux OS version via the GUI by heading to the system settings and locating the 'Details' or 'About' section, depending on your particular distribution. Why do various Linux distributions have unique version numbering systems? Each Linux distribution is developed and maintained by a different community or organization. Consequently, they all have unique version numbering systems to monitor progress and schedule future releases. For instance, Ubuntu's version number format is 'XX.YY.ZZ', where 'XX' denotes the year, 'YY' indicates the month of release, and 'ZZ' increments with each new release within that month. Conclusion Linux OS versions vary in underlying architecture, package management system, desktop environment, security features, compatibility, and release cycles. Each version has its own unique set of features and benefits, so users can choose the one that best suits their needs and preferences. Understanding your Linux OS version helps you in troubleshooting and solving problems, providing a better insight into the system's capabilities and limitations, allowing you to make informed decisions when it comes to upgrading or modifying the system. Now you have learned the different methods on how to check OS version in Linux through special commands or using GUI. Choose the best way for yourself and use it. Regularly checking and updating your Linux OS version is a good practice to ensure productive and hassle-free operation of your computer. This ensures that the system is running the latest version and all necessary security protocols are installed. If you're already found out your Linux version, don't forget to check how to create a server image on Linux.
30 May 2025 · 11 min to read

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