Basic commands for Debian system administration

Debian is a Linux operating system widely used in servers and workstations. As a systems administrator on Debian, it is fundamental to be familiar with the basic commands to perform maintenance, configuration, and monitoring tasks. This manual will provide you with a practical guide to the essential commands that will allow you to manage and maintain a Debian system efficiently.

1. System Information Commands

• uname -a: Displays detailed information about the system, such as the kernel name, architecture, and hostname.

• lsb_release -a: Displays information about the installed Debian distribution, such as the version and description.

• df -h: Displays used and available disk space on all system partitions.

• free -h: Displays used and available RAM memory in the system.

2. User and Group Management

• adduser username: Creates a new user on the system.

• usermod -aG group username: Adds a user to a specific group.

• deluser username: Deletes a user from the system.

• addgroup group_name: Creates a new group on the system.

3. Package Management

• apt update: Updates the list of available packages in the repositories.

• apt upgrade: Updates installed packages to the most recent versions.

• apt install package_name: Installs a specific package.

• apt remove package_name: Uninstalls a package from the system.

• apt search package_name: Searches for packages related to a specific term.

4. Service Management

• systemctl status service_name: Displays the status of a service.

• systemctl start service_name: Starts a service.

• systemctl stop service_name: Stops a service.

• systemctl restart service_name: Restarts a service.

• systemctl enable service_name: Enables a service to start automatically at system boot.

• systemctl disable service_name: Disables a service from starting automatically at system boot.

5. Network Configuration

• ifconfig: Displays information about the configured network interfaces.

• ip addr: Displays more detailed information about network interfaces and their IP addresses.

• ping ip_address: Sends ICMP packets to an IP address to verify network connectivity.

• nslookup hostname: Performs a DNS query to obtain the IP address associated with a hostname.

6. File and Directory Management

• ls: Lists the contents of the current directory.

• pwd: Displays the path of the current directory.

• cd directory_path: Changes to the specified directory.

• mkdir directory_name: Creates a new directory.

• rm file_name: Deletes a file.

• rm -r directory_name: Deletes a directory and its contents recursively.

7. Compressing and Decompressing Files

• tar -cvf file.tar directory: Creates a tar archive from a directory.

• tar -xvf file.tar: Extracts the contents of a tar archive.

• gzip file: Compresses a file in gzip format.

• gunzip file.gz: Decompresses a file compressed in gzip format.

8. Process Management

• ps: Displays a list of processes currently running on the system.

• ps aux: Displays a more detailed list of all processes on the system, including those of other users.

• top: Provides a dynamic, real-time view of running processes, with periodically updated information.

• htop: An improved version of top that displays processes in a more readable format and allows interacting with them more easily.

• kill PID: Terminates (kills) a specific process using its process identifier (PID).

• killall process_name: Terminates all processes that have the same name. Be careful when using it, as it can stop important processes.

• nice: Adjusts the priority of a process. You can use it to change the priority of a process and give it more or fewer system resources.

• renice: Changes the priority of a running process. It is useful for adjusting the priority of processes running in real time.