Other Common Questions

What Are the Differences Between Debian and Ubuntu

Debian and Ubuntu are two of the most closely related Linux distributions. Ubuntu is built on Debian's unstable (Sid) branch, but they differ significantly in philosophy, release cycle, and target audience.

Feature	Debian	Ubuntu
Philosophy	Community-driven, 100% free software (by default). Pursues stability and software freedom, maintained by a global community of volunteers.	Led by a commercial company (Canonical). Pursues ease of use and the latest features, includes proprietary drivers and software, and is more beginner-friendly.
Release Cycle	Slow and steady. The Stable release publishes a major version approximately every 2 years. After a version is released, software is essentially frozen, with only security updates provided.	Fast and fresh. A new version is released every 6 months, with a Long Term Support (LTS) version every 2 years. Software versions are updated more frequently.
Stability	Extremely stable (Stable branch). Regarded as one of the most stable Linux distributions, making it an ideal choice for servers.	Relatively stable (LTS versions). LTS versions are thoroughly tested and suitable for most users and production environments. However, non-LTS versions tend to be more experimental.
Software Repositories	By default, only free software is included. non-free and contrib must be manually enabled by the user. Software versions are older, but newer versions can be obtained via Backports.	Includes a large amount of non-free firmware and drivers by default for out-of-the-box convenience. Provides PPAs (Personal Package Archives) for easy installation of third-party software.
Ease of Use	The installation and configuration process is more "vanilla," requiring users to have some Linux knowledge.	The installation process is highly graphical and extremely beginner-friendly. Provides many additional tools and driver managers to simplify configuration.
Desktop Environment	Provides an unmodified, vanilla GNOME desktop by default. Also offers installation options for all other major desktop environments.	Uses a GNOME desktop heavily customized by Canonical, integrated with its own themes and extensions.

Summary: Which Should I Choose?

• Choose Debian if you are:

  • A server administrator or developer seeking ultimate stability and reliability.
  • Looking to build a clean, lightweight system without unnecessary modifications.
  • Aligned with the free software philosophy.
  • Experienced with Linux and willing to spend time on manual configuration.

• Choose Ubuntu if you are:

  • A Linux beginner looking for an "out-of-the-box" experience.
  • A desktop user who wants to easily install the latest software and proprietary drivers (such as NVIDIA drivers).
  • In need of software available through a large number of PPA repositories.

To put it simply, Debian is like a piece of high-quality lumber — you can craft anything you want from it; Ubuntu is like IKEA furniture — ready to use right out of the box, slightly less customizable, but convenient and quick.

How to Compile and Install Software on Debian

Compiling and installing software from source code is typically a last resort for obtaining software that is not available in the official repositories or that requires specific compilation options. This process is commonly referred to as "make install."

Warning: Software installed via make install is not tracked by the apt package manager. This means apt is unaware of its existence and cannot provide updates, handle dependencies, or cleanly uninstall it when it is no longer needed. This can lead to so-called "dependency hell" or cluttered system files.

Before compiling, consider the following alternatives first:

1. Use the Backports repository.
2. Use Flatpak or Snap.
3. Look for official or unofficial .deb packages.

Standard Compilation and Installation Steps (./configure && make && sudo make install)

1. Install the build toolchain:

   sudo apt install build-essential

   build-essential is a meta-package that installs a set of tools required for compilation, such as gcc (C compiler), g++ (C++ compiler), and make.

2. Resolve build dependencies:

   • This is the most critical and error-prone step. Almost all software depends on other library files for compilation. You need to read the README or INSTALL file included in the software's source package, which will list all required dependencies.
   • You need to manually install these dependency packages using apt. Note that you need to install the development packages (usually ending in -dev). For example, if the software requires libpng, you need to install libpng-dev.

3. Extract the source code and enter the directory:

   tar -xvf software-1.2.3.tar.gz
   cd software-1.2.3

4. Configure (configure):

   • Run the ./configure script. This script checks your system environment, ensures all dependencies are met, and generates a Makefile.
   • You can customize features via parameters. For example, --prefix lets you specify the installation path.

     ./configure --prefix=/usr/local

     If prefix is not specified, the default installation location is usually under /usr/local in the bin, lib, share, and other directories. This helps keep it separate from the system package management path (/usr).

5. Compile (make):

   • Run the make command. This process invokes the compiler (such as gcc) to convert source code into executable binary files.
   • If your CPU has multiple cores, you can use the -j parameter for parallel compilation to speed things up. For example, make -j4 (using 4 cores).

6. Install (make install):

   • Run sudo make install. This command copies the compiled files, documentation, and configuration files from the previous step to the system directories you specified during the configure step. sudo is required because it writes to system directories.

How to Uninstall: Since apt is unaware of these files, you cannot use apt remove to uninstall them.

• Best method: Run sudo make uninstall from the source code directory. However, not all software authors provide this feature.
• Manual deletion: If you specified a prefix during configure, you can manually delete the files from the corresponding directory. But this is a tedious and error-prone process.

How to View Log Files on Debian

Linux system logs are a treasure trove for troubleshooting. Modern Debian systems primarily use systemd-journald to manage logs.

Using journalctl (Recommended)

journalctl is a powerful tool for viewing journald logs.

• View all logs (oldest to newest):

  journalctl

  (Press q to quit, use arrow keys and PageUp/Down to navigate)

• View all logs in reverse order (newest to oldest):

  journalctl -r

• Monitor logs in real time:

  journalctl -f

  This continuously displays newly generated logs, which is very useful for monitoring ongoing events.

• View all logs since the current boot:

  journalctl -b

• View logs from the previous boot:

  journalctl -b -1

• Filter by time:

  # View all logs from today
  journalctl --since=today
  # View logs from the past hour
  journalctl --since="1 hour ago"

• Filter by service unit:

  # View only SSH service logs
  journalctl -u ssh.service

• Filter by priority (view error messages):

  • p stands for priority.

  # View only error level (error, level 3) and above logs
  journalctl -p 3
  # View errors from the current boot
  journalctl -p 3 -b

The Traditional /var/log Directory

Although journald is the mainstream approach, many traditional services and applications still store their log files as plain text in the /var/log directory.

• View general system logs:

  • cat /var/log/syslog
  • cat /var/log/messages

• View authentication-related logs (e.g., login, sudo):

  • cat /var/log/auth.log

• View kernel logs:

  • cat /var/log/kern.log
  • Or use the dmesg command.

• View APT package management logs:

  • cat /var/log/apt/history.log

To view these files, you can use commands such as cat, less, more, or tail -f (real-time monitoring). For example, tail -f /var/log/syslog.