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As you are performing your sysadmin tasks, some users may try to connect to your server in order to perform their daily tasks.

However, in some cases, you may find that something has changed on your server. As a consequence, you are wondering who performed the change.

Luckily for you, there are many ways to find who last logged in on your server.

As a system administrator, you probably already know how important it is to encrypt your disks.

If your laptop were to be stolen, even a novice hacker would be able to extract the information contained on the disks.

All it takes is a simple USB stick with a LiveCD on it and everything would be stolen.

Luckily for you, there are ways for you to prevent this from happening : by encrypting data stored on your disks.

As a system administrator, you are probably dealing with a lot of services every day. They may be used in order to start a SSH server on your machine or they can perform some operations on a specific hour or day. In this tutorial, you will learn how you can, given your system manager, list all services on your Linux machine.

As announced on the Ubuntu official website, Canonical has just released a brand new version of Ubuntu on the 23th of April 2020. This tutorial provides step by step instructions on how to install Ubuntu 20.04 with a GNOME environment. It covers the very first steps of server creation using the graphical installation of Ubuntu Focal Fossa.

On Docker images, you may choose to have a specific operating system, to install specific packages or to execute a set of predefined commands. However, if you create multiple environments or multiple tools, your list of Docker images will be growing quickly. As a consequence, you may need commands in order to list your Docker images easily. In this tutorial, you are going to learn how you can list your Docker images using Docker commands.

If you are working as a system or a network administrator, you probably need to find MAC addresses everyday. MAC addresses represent a very valuable source of information : they uniquely identify computers, more precisely network cards, over a network. In this tutorial, you are going to learn how you can easily find your MAC address on Linux.

Copying directories on Linux is a big part of every system administrator routine. If you have been working with Linux for quite some time, you know how important it is to keep your folders well structured. In some cases, you may need to copy some directories on your system in order revamp your main filesystem structure. In this tutorial, we are going to see how you can easily copy directories and folders on Linux using the cp command.

If you are working on a small to medium entreprise network, you probably have dozens of drives and printers that need to be shared. Besides the NFS protocol, there are plenty of other network protocols that can be used in order to share resources over a network. The CIFS, short for Common Internet File System, is a network filesystem protocol used to share resources among multiple hosts, sharing the same operating system or not. The CIFS, also known as the SMB protocol, is implemented by one popular tool : the Samba server.

As a system administrator, you are probably monitoring the disk space on your system all the time. When browsing directories on your server, you might have come across directories with a lot of files in them. Sometimes, you may want to know how many files are sitting in a given directory, or in many different directories. In other words, you want to count the number of files that are stored in a directory on your system.

When working with Bash and shell scripting, you might need to use conditions in your script. In programming, conditions are crucial : they are used to assert whether some conditions are true or not. In this tutorial, we are going to focus on one of the conditional statement of the Bash language : the Bash if else statement.

Used by system administrators on a daily basis, the ping command, relying on the ICMP protocol, retrieves operational information about remote hosts.

However, pinging hosts is not always sufficient : you may need to ping a specific port on your server. This specific port might be related to a database, or to an Apache web server or even to a proxy server on your network.

Whether this is on a Windows domain controller, or on a Linux OpenLDAP server, the LDAP protocol is very useful to centralize authentication. However, as your LDAP directory grows, you might get lost in all the entries that you may have to manage. Luckily, there is a command that will help you search for entries in a LDAP directory tree : ldapsearch.

When working on a project, you are probably managing many different branches in your repository. As the number of branches grow, you may need to work on different tasks in parallel, going from one branch to another all the time. As a consequence, you may need to switch branches very frequently.

From all the compression methods available, Zip is probably one of the most popular ones.

Released in 1989 by Philip Katz, Zip is widely used by system administrators in order to reduce the size of bulky files and directories on your system.

In this tutorial, we are going to see how you can easily zip folders and directories on Linux using the zip command.

If you followed our previous articles on writing Git commit messages, you know how important it can be to write insightful and descriptive commit messages.

However, in some cases, you probably created your commits already and you will need to amend your Git commit message.

In this tutorial, you will learn how you can amend your Git commit message easily.

Git commit messages are crucial : they are used in order to describe and share with others what you did. They are also used when trying to hotfix issues happening on your master branches. In this tutorial, you are going to learn how you can create Git commits with messages.

Git branches are created in order to isolate specific Git commits from the rest of your main Git history. If you main Git history is based on the master branch, you can create a separate Git branch in order to develop new features and merge them later on.

In this tutorial, we are going to see how you can easily create a Git branch.

Getting your IP address is often the first step of most network troubleshooting processes. If you are trying to reach a website but the website is no answering back, it might be because your network adapter is badly configured. Similarly, you might want to reach internal addresses, but if your IP address is configured in the wrong subnet, you won’t be able to ping them. In this tutorial, we are going to see how you can get your IP address on Linux easily.

If you are a web developer or a software engineer, it is very likely that you are pushing a lot of commits to your Git repository everyday. However, in some cases, you committed some files that should not be pushed to your Git repository. Sometimes, you may want to perform additional changes before issuing the commit. As a consequence, you need to undo the last commit from your Git repository. In this tutorial, we are going to see how you can easily undo the last commit, maybe to re-commit changes later on.

In order to start working with Git, you can either create your own Git repository or you can clone an existing Git repository. In this tutorial, we are going to focus on cloning an existing Git repository. We are also going to see different ways to clone a specific branch, to clone using a SSH key and to solve access denied issues.