Deleting a User in Ubuntu 22.04
Ubuntu
04.07.2025
Reading time: 7 min
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A server administrator often has to work with user accounts — adding, deleting, and configuring access modes. Removing outdated user accounts is one security measure that can significantly reduce the number of vulnerabilities in the system.
The Linux utilities deluser and userdel are used for deletion. However, before proceeding directly to deleting a user, we must take certain steps.
In this article, we will explore how to delete a user in Ubuntu without compromising the system. At the same time, we will preserve the ability to access the user’s home directory files after deletion. In this article, we will work with the user hostman, which was created beforehand.
This article will primarily focus on removing an Ubuntu user via the terminal, but we will also provide instructions for deleting a user account through the graphical interface.
Please note that you will need superuser privileges to work with user accounts.
And if you’re looking for a reliable, high-performance, and budget-friendly solution for your workflows, Hostman has you covered with Linux VPS Hosting options, including Debian VPS, Ubuntu VPS, and VPS CentOS.
The instructions below will be suitable for any cloud server running Ubuntu OS.
Checking the User Account
First, you need to check whether the user is currently logged into the system. This will affect further steps: if the user is currently authorized on the server, you will need to terminate their connection and change the password.
Check the list of users authorized in the system using the who utility or its alias w:
whoIf you see that the user hostman is authorized, you need to check which processes are running under this user. This is a necessary step because if background operations are being performed, Ubuntu 22.04 will not allow us to delete the user. Check with the ps utility:
sudo ps -u hostmanAs a result, you might see a response like this:
PID TTY TIME CMD
1297129 pts/2 00:00:00 bash
1297443 pts/2 00:00:00 htopFor testing purposes, we launched the htop utility under the hostman account, which is running in the background.
Blocking Access
Before stopping the user’s processes, you need to block their access to the system. You can do this by changing their password.
User passwords are stored in the system in encrypted form in the /etc/shadow file. This file is readable only by the root user, and in addition to password hashes, it contains their expiration information.
There is a special utility that allows you to remove a user’s password in Ubuntu — passwd. To restrict access, we will use the passwd utility with the -l (or --lock) flag, which puts the utility into lock mode:
sudo passwd -l hostmanAs a result, the utility will add an exclamation mark at the beginning of the encrypted password string. That is all that is needed to prevent the user from logging in again since the hashes will no longer match.
Killing Processes
In Ubuntu, you cannot delete a user via the console if any processes are running under their name. To terminate a process, you can use one of the following commands:
-
kill— deletes a process by its identifier. You can determine the IDs of thehostmanuser processes with:
top -U hostman or ps -u hostman-
pkill— deletes a process by its name. For example, if the userhostmanhas launched thetopprocess, you can terminate it with:
sudo pkill top-
killall— deletes all processes, including child processes. Often, a process will launch many so-called subprocesses; stopping them by name or identifier can be complex and time-consuming.
We will use the last command to reliably kill all user processes:
sudo killall -9 -u hostmanThe -9 flag means the processes will receive a SIGKILL signal. This means the process will be forcibly terminated, since this signal cannot be ignored or blocked. Essentially, it is equivalent to a “force quit” of a non-responding program in graphical operating systems.
After completing the user’s processes, they will no longer be authorized in the system. You can verify this using the who command. Since we locked the login in the previous step, the hostman user will not be able to log in again.
Optional — Archiving the Home Directory
Quite often, when deleting a Linux user account, you may need to keep its home directory, which might contain important files required either by the user or by the organization you are serving as an administrator.
The built-in Ubuntu utilities allow you to remove a user while keeping their home directory. However, this is not recommended for two reasons:
-
Disk Space — the user’s home directory may contain a large amount of data. It is irrational and excessive to store data from all outdated accounts on the main work disk. Over time, you might run out of space for new users.
-
Data Relevance — it is good practice to keep the
/homedirectory containing only the directories corresponding to active user accounts. Keeping this list in order helps with administration.
We will use the tar utility to archive the home directory of the hostman user:
sudo tar -cvjf /mnt/nobackup/hostman.homedir.tar.gz /home/hostmanLet’s go over the arguments and flags:
-c— creates the resulting.tararchive file-v— enables verbose mode, showing debugging information and listing archived files-z— creates a compressed.gzarchive-f— indicates that the first argument will be used as the archive name
The first argument is the final location of the archive. In our example, we place the archive with the user’s home directory on the nobackup disk, which, as the name implies, is not subject to backup.
The second argument is the path to the directory from which the archive is created.
Stopping Scheduled Jobs
Before deleting a user in Ubuntu, it is recommended to stop all cron scheduler tasks launched by that user. You can do this with the crontab command. We will launch it under the hostman user with the -u flag and switch it to delete mode with the -r flag:
sudo crontab -r -u hostmanNow you can be sure that after deleting the user account, no unknown scripts will be executed for which no one is responsible.
Deleting the User
Once all the previous steps have been completed, it is time to proceed with the main task: deleting the Ubuntu user. There are two ways to do this: the deluser and userdel utilities.
To delete the user account, we will use the deluser utility. Running it without parameters will delete the user account but leave their home directory and other user files intact. You can use the following flags:
-
--remove-home— as the name suggests, deletes the user’s home directory -
--remove-all-files— deletes all system files belonging to the user, including the home directory -
--backup— creates an archive of the home directory and mail files and places it in the root directory. To specify a folder for saving the archive, use the--backup-toflag.
As you can see from the parameter descriptions above, manually archiving the user’s home directory is not strictly necessary — deluser can do everything for you. In addition, with deluser you can remove a user from a group in Ubuntu or delete the group itself:
sudo deluser hostman administratorsThe command above removes the user hostman from the administrators group.
Let’s proceed with the complete deletion of the user and the hostman group without preserving the home directory:
sudo deluser --remove-home hostmanDeleting the User via Graphical Interface
The entire article above is about how to delete a user in the Ubuntu terminal. But if you have a system with a graphical interface, you can delete a user in just a few simple steps.
Open the Users section in System Settings. To switch to superuser mode, click the Unlock button. After that, the Delete User button will become active. When you click it, a dialog box will appear, offering to delete the user’s files, specifically those in the home directory.
Conclusion
Deleting a user in Ubuntu is not difficult; you just need to use the deluser utility with the required parameters. However, in this article, we described several steps that will help you safely delete a user account while preserving the system’s stability.
Ubuntu
04.07.2025
Reading time: 7 min
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Ubuntu
Installing and Configuring cloud-init on Ubuntu
cloud-init is the de facto industry standard for automated initialization of virtual machines in cloud environments. This powerful configuration tool is activated at the first boot of an instance and allows execution of a predefined set of tasks without manual intervention.
Its key functions include:
Automating basic system setup, including assigning a hostname.
User account management: creating users, assigning permissions, and configuring authentication mechanisms.
Automatic deployment of SSH keys for secure access.
Configuration of network interfaces according to specified parameters.
Operations with disk storage, such as mounting and formatting volumes.
Execution of custom scripts for post-installation configuration, which may include installing software, deploying application code, and applying fine-tuned settings.
Although cloud-init is primarily designed for public clouds (AWS, Google Cloud, Azure, Hostman), it can also be used on local virtual machines and even on physical servers to standardize their initial setup.
And if you’re looking for a reliable, high-performance, and budget-friendly solution for your workflows, Hostman has you covered with Linux VPS Hosting options, including Debian VPS, Ubuntu VPS, and VPS CentOS.
In this article, we will look at how to install, configure, and use cloud-init on Ubuntu.
Installation
In most Ubuntu images, cloud-init is already preinstalled. Canonical (the developer of Ubuntu) also releases images called Ubuntu Cloud Images, specially prepared and optimized for running in cloud environments.
In Hostman, all Ubuntu images already include cloud-init.
You can additionally check for cloud-init with the command:
cloud-init --version
If the command outputs a version (as shown in the screenshot above), then cloud-init is already installed in the system. If the response is Command cloud-init not found, install the utility with:
apt update && apt -y install cloud-init
After installation, cloud-init will automatically run at every system boot. Note that cloud-init runs before the server connects to the network.
Configuration File Structure
All cloud-init configuration files are located in /etc/cloud/:
/etc/cloud/clean.d/ — directory for cleanup scripts. These scripts are executed when the command cloud-init clean is run.
/etc/cloud/cloud.cfg — the main configuration file. This sets the default settings for all initialization stages.
/etc/cloud/cloud.cfg.d/ — directory for user configuration files with the .cfg extension. Files are processed in alphabetical order and override settings from the main file. This is the preferred location for custom configurations.
/etc/cloud/templates/ — contains templates used by cloud-init to generate system files.
/var/lib/cloud/ — stores cache, data, and scripts generated during cloud-init execution.
Modules
Modules in cloud-init are separate executable components that perform specific configuration tasks when a VM first boots. Each module is responsible for its own area: network configuration, user creation, package installation, etc.
An important feature of modules is their execution order: they do not run randomly, but in a strict sequence consisting of stages:
Init Stage (Initialization stage): Runs immediately after mounting the root filesystem. Modules needed to prepare the system for main configuration are executed here (e.g., mounting additional disks).
Config Stage (Configuration stage): The main stage where most modules run: network setup, package installation, SSH key setup, user creation.
Final Stage: Executes modules for tasks that should occur at the very end, such as sending system readiness notifications or running user scripts.
Local Usage of cloud-init
Let’s test cloud-init locally, i.e., run it after the server has already booted. We will create two scenarios:
The first scenario will create a new user named new-admin, assign a password, and grant administrator rights.
The second scenario will install the packages atop, tree, net-tools.
Since we will use a password for the new user, we need to generate its hash, as all passwords (and other secrets) are specified in plain text by default. . To get a hash, install the whois package, which contains the mkpasswd utility:
apt -y install whois
Run the utility with the SHA-512 hashing algorithm:
mkpasswd -m sha-512 --stdin
Enter the password for the user and press Enter. The utility will generate a password hash.
Copy this hash for later use.
As noted earlier, user configuration files are stored in /etc/cloud/cloud.cfg.d. Create a new file 99-new-admin-config.cfg:nano /etc/cloud/cloud.cfg.d/99-new-admin-config.cfg
Use the following content:
#cloud-config
users:
- name: new-admin
passwd: $6$BSAzGG4SFvsn//vD$ds8oM53OIs6qXiCIhMTl10bwQfe9u5WxGKADzwyPsODniGhYAXCUOAoyUkJLs.H9z0PxqLr7BxEJ18hT2VEyR/
sudo: ALL=(ALL) ALL
shell: /bin/bash
groups: sudo
Check syntax for errors:
cloud-init schema --config-file /etc/cloud/cloud.cfg.d/99-new-admin-config.cfg
If there are no errors, the command will return Valid schema.
Before running the script, clear the previous configuration:
cloud-init clean
Run the configuration:cloud-init single --name users-groups --file /etc/cloud/cloud.cfg.d/99-new-admin-config.cfg
After the new configuration is applied, check for the new-admin user:
id new-admin
Next, install the packages. Create a new file:
nano /etc/cloud/cloud.cfg.d/99-install-packages.cfg
Use the following content:
#cloud-config
package_update: true
package_upgrade: true
packages:
- atop
- tree
- net-tools
Check syntax:
cloud-init schema --config-file /etc/cloud/cloud.cfg.d/99-install-packages.cfg
Clear configuration:
cloud-init clean
Run the script to install the packages:
cloud-init single --name package_update_upgrade_install --file /etc/cloud/cloud.cfg.d/99-install-packages.cfg
Verify the installed packages:
dpkg -l | grep -E "atop|tree|net-tools"
Using cloud-init in Hostman
Hostman cloud servers running Linux support cloud-init via the control panel. Scenarios can be configured both during server ordering and later during usage. Let’s look at the practical use of cloud-init.
We will create a scenario that will:
Create a new user named new-usr;
Configure SSH key authentication for new-usr;
Install two packages: mc, ncdu;
Change the hostname to hostman-server;
Create a file test-file.txt in the /tmp directory.
If cloud-init scripts have already been run on the server, run cloud-init clean before applying the configuration below.
Our script will run when creating a virtual server; we can add it at step 7:
Since SSH key authentication will be used for the new user, generate keys in advance. On another device (Windows, macOS, Linux), run the command:
ssh-keygen
Save the keys in the default directory (.ssh in the home directory). Then obtain the public key value (.pub file):
cat ~/.ssh/id_ed25519.pub
Replace id_ed25519.pub with your own filename if different.
In the control panel, in the cloud-init block, enter the following syntax:
#cloud-config
packages:
- mc
- ncdu
users:
- name: "new-usr"
groups: sudo
shell: /bin/bash
sudo: ['ALL=(ALL) NOPASSWD:ALL']
ssh_authorized_keys:
- ssh-rsa AAAAC3NzaC1lZDI1NTE5AAAAIFoUTI5BKDBDgKLIMpM71m/YI7dTtFKQiSIivRk9pUbs alex@DESKTOP-VTUJHJ9
lock_passwd: true
hostname: hostman-server
preserve_hostname: false
runcmd:
- [touch, /tmp/test-file.txt]
In the ssh_authorized_keys field, enter your own public key.
Complete the server order by clicking “Order.”
Once the server is created, connect via SSH with the new user and verify that all specified actions were completed.
Verify the user:
id new-usr
Verify installed packages:
dpkg -l | grep -E "mc|ncdu"
Verify hostname:
hostname
Verify file existence:
ls -lah /tmp/test-file.txt
Conclusion
cloud-init is a powerful tool for automating the initial setup of servers in Ubuntu. With its capabilities, you can deploy fully configured servers in seconds, minimize human error, and easily scale infrastructure.
The main strength of cloud-init lies in its ability to transform a virtual machine template into a fully configured, production-ready server instance without manual intervention. Automating network configuration, security updates, user creation, and software deployment are the advantages that make it indispensable for DevOps engineers and system administrators.
04 September 2025 · 7 min to read
Java
Switching between Java Versions on Ubuntu
Managing multiple Java versions on Ubuntu is essential for developers working on diverse projects. Different applications often require different versions of the Java Development Kit (JDK) or Java Runtime Environment (JRE), making it crucial to switch between these versions efficiently. Ubuntu provides powerful tools to handle this, and one of the most effective methods is using the update-java-alternatives command.
Switching Between Java Versions
In this article, the process of switching between Java versions using updata-java-alternatives will be shown. This specialized tool simplifies the management of Java environments by updating all associated commands (such as java, javac, javaws, etc.) in one go.
And if you’re looking for a reliable, high-performance, and budget-friendly solution for your workflows, Hostman has you covered with Linux VPS Hosting options, including Debian VPS, Ubuntu VPS, and VPS CentOS.
Overview of Java version management
A crucial component of development is Java version control, especially when working on many projects with different Java Runtime Environment (JRE) or Java Development Kit (JDK) needs. In order to prevent compatibility problems and ensure efficient development workflows, proper management ensures that the right Java version is utilized for every project.
Importance of using specific Java versions
You must check that the Java version to be used is compatible with the application, program, or software running on the system. Using the appropriate Java version ensures that the product runs smoothly and without any compatibility issues.
Newer versions of Java usually come with updates and security fixes, which helps protect the system from vulnerabilities. Using an out-of-date Java version may expose the system to security vulnerabilities.
Performance enhancements and optimizations are introduced with every Java version. For maximum performance, use a Java version that is specific to the application.
Checking the current Java version
It is important to know which versions are installed on the system before switching to other Java versions. To check the current Java version, the java-common package has to be installed. This package contains common tools for the Java runtimes including the update-java-alternatives method. This method allows you to list the installed Java versions and facilitates switching between them. Use the following command to install the java-common package:
sudo apt-get install java-common
Upon completing the installation, verify all installed Java versions on the system using the command provided below:
sudo update-java-alternatives --list
The report above shows that Java versions 8 and 11 are installed on the system. Use the command below to determine which version is being used at the moment.
java -version
The displayed output indicates that the currently active version is Java version 11.
Installing multiple Java versions
Technically speaking, as long as there is sufficient disk space and the package repositories support it, the administrator of Ubuntu is free to install as many Java versions as they choose.
Follow the instructions below for installing multiple Java versions.
Begin by updating the system using the following command:
sudo apt-get update -y && sudo apt-get upgrade -y
To add another version of Java, run the command below.
sudo apt-get install <java version package name>
In this example, installing Java version 17 can be done by running:
sudo apt-get install openjdk-17-jdk openjdk-17-jre
Upon completing the installation, use the following command to confirm the correct and successful installation of the Java version:
sudo update-java-alternatives --list
Switching and setting the default Java version
To switch between Java versions and set a default version on Ubuntu Linux, you can use the update-java-alternatives command.
sudo update-java-alternatives --set <java_version>
In this case, the Java version 17 will be set as default:
sudo update-java-alternatives --set java-1.17.0-openjdk-amd64
To check if Java version 17 is the default version, run the command:
java -version
The output shows that the default version of Java is version 17.
Managing and Switching Java Versions in Ubuntu
Conclusion
In conclusion, managing multiple Java versions on Ubuntu Linux using update-java-alternatives is a simple yet effective process. By following the steps outlined in this article, users can seamlessly switch between different Java environments, ensuring compatibility with various projects and taking advantage of the latest features and optimizations offered by different Java versions. Because Java version management is flexible, developers may design reliable and effective Java apps without sacrificing system performance or stability.
22 August 2025 · 4 min to read
Ubuntu
How to Install and Configure SSH on Ubuntu 22.04
A secure connection between a client and a server is made possible via the SSH network protocol. Since all communications are encrypted, distant network attacks and data theft across the network are avoided.
Let’s say you have ordered a cloud server from Hostman. You will need SSH installed and configured to connect to and administer the server.
The guide below will describe how to install SSH on Ubuntu 22.04 and configure it.
SSH Key configuration is pretty simple on Ubuntu
Prerequisites
Before proceeding with the installation and configuration of the Secure Shell service, ensure the following requirements are met:
Linux Command Line Skills for Configuration
Having a solid grasp of basic Linux commands like sudo, apt, nano, and systemctl is essential when setting up the service. These commands will be frequently used during the installation and configuration process. It's crucial to be comfortable working within the command line environment to manage the service effectively.
Root or Sudo Access for Setup
To install and configure the server, administrative (root) privileges are required. Users must either have sudo access or be logged in as root. Without these privileges, the setup process cannot proceed.
Internet Connection for Package Download
A stable internet connection is necessary to install the OpenSSH server and any additional related packages. Without a functional connection, the system cannot retrieve the required software components.
Configuring Firewall for Access
If a firewall, like ufw, is enabled on the system, it may block remote access by default. It is essential to configure your firewall to allow incoming connections. Use ufw or another firewall tool to ensure port 22 is open and accessible.
Access to the System (Local or Remote)
To configure the service locally, you must have physical access to your computer; otherwise, it must be remotely accessible through its IP address. To connect, make sure the system is correctly linked to the network.
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Step 1: Prepare Ubuntu
The first thing you need to do before you start installing SSH on Ubuntu is to update all apt packages to the latest versions. To do this, use the following command:
sudo apt update && sudo apt upgrade
Step 2: Install SSH on Ubuntu
OpenSSH is not pre-installed on the system, so let's install it manually. To do this, type in the terminal:
sudo apt install openssh-server
The installation of all the necessary components will begin. Answer "Yes" to all the system prompts.
After the installation is complete, go to the next step to start the service.
Step 3: Start SSH
Now you need to enable the service you just installed using the command below:
sudo systemctl enable --now ssh
On successful startup, you will see the following system message.
The --now key helps you launch the service and simultaneously set it to start when the system boots.
To verify that the service is enabled and running successfully, type:
sudo systemctl status ssh
The output should contain the Active: active (running) line, which indicates that the service is successfully running.
If you want to disable the service, execute:
sudo systemctl disable ssh
It disables the service and prevents it from starting at boot.
Step 4: Configure the firewall
Before connecting to the server via SSH, check the firewall to ensure it is configured correctly.
In our case, we have the UFW installed, so we will use the following command:
sudo ufw status
In the output, you should see that SSH traffic is allowed. If you don't have it listed, you need to allow incoming SSH connections. This command will help with this:
sudo ufw allow ssh
Step 5: Connect to the server
Once you complete all the previous steps, you can log into the server using the SSH protocol.
You will need the IP address or domain name of the server as well as the name of a user that was created on the server in order to complete this step.
In the terminal line, enter the command:
ssh username@IP_address
Or:
ssh username@domain
Important: To successfully connect to a remote server, SSH must be installed and configured on the remote server and the user's computer from which you make the connection.
-
Step 6 (optional): Create Key Pair for Secure Authentication
For enhanced security, consider configuring a key pair instead of relying on password authentication. To generate one, use the following command:
ssh-keygen
Step 7: Configure SSH
Having completed the previous five steps, you can already connect to the server remotely. However, you can further increase the connection's security by changing the default connection port to another or changing the password authentication to key authentication. These and other changes require editing the SSH configuration file.
The main OpenSSH server settings are stored in the main configuration file sshd_config (location: /etc/ssh). Before you start editing, you should create a backup of this file:
sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.initial
If you get any errors after editing the configuration file, you can restore the original file without problems.
After creating the backup, you can proceed to edit the configuration file. To do this, open it using the nano editor:
sudo nano /etc/ssh/sshd_config
In the file, change the port to a more secure one. It is best to set values from the dynamic range of ports (49152 - 65535) and use different numbers for additional security. For example, let's change the port value to 49532. To do this, we uncomment the corresponding line in the file and change the port as shown in the screenshot below.
SSH Key Configuration Description in Linux Terminal
In addition to this setting, we recommend changing the password authentication mode to a more secure key authentication mode. To do this, uncomment the corresponding line and make sure the value is "Yes", as shown in the screenshot.
Authentication Key should be Enabled
Now, let's prohibit logging on to the server as a superuser by changing the corresponding line as shown in the picture below.
Don't Forget to Close Access to Root Login
There are other settings you can configure to increase the server security:
UseDNS checks if the hostname matches its IP address. The value "Yes" enables this parameter.
PermitEmptyPasswords prohibits using empty passwords for authentication if the value is "No."
MaxAuthTries limits the number of unsuccessful attempts to connect to the server within one communication session.
AllowUsers and AllowGroups are responsible for the list of users and groups allowed to access the server:
# AllowUsers User1, User2, User3# AllowGroups Group1, Group2, Group3
Login GraceTime sets the time provided for successful authorization. We recommend reducing the value of this parameter by four times.
ClientAliveInterval limits the time of user inactivity. After exceeding the specified limit, the user is disconnected.
After making all the changes in the main configuration file, save them and close the editor.
Restart the service to make the changes take effect:
sudo systemctl restart ssh
If you have changed the port in the configuration file, you should connect using the new port:
ssh -p port_number username@IP_address
Or:
ssh -p port_number_port_username@domain
Troubleshooting Connection Issues
Ensure the service is running with:
sudo systemctl status ssh
Restart it if necessary:
sudo systemctl restart ssh
Check firewall settings to allow traffic on port 22:
sudo ufw allow 22
Confirm the system is reachable by running:
ping <server-ip-address>
Disabling the Service
If you need to disable remote access for any reason, follow these steps:
Stop the Service
To temporarily stop accepting connections:
sudo systemctl stop ssh
Prevent Automatic Startup
To disable it from starting on reboot:
sudo systemctl disable ssh
Confirm Inactive Status
Verify that the service is no longer running:
sudo systemctl status ssh
Uninstall the Server
If the service is no longer needed, remove it and its associated configuration files:
sudo apt remove openssh-server
Conclusion
This article presents a step-by-step guide on installing and configuring SSH in Ubuntu 22.04 and describes how to edit the main configuration file to improve security. We hope this guide helps you to set up a secure remote connection to your Ubuntu server.
And if you’re looking for a reliable, high-performance, and budget-friendly solution for your workflows, Hostman has you covered with Linux VPS Hosting options, including Debian VPS, Ubuntu VPS, and VPS CentOS.To see more about SSH keys click here.
21 August 2025 · 7 min to read
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