Читать книгу Mastering Linux System Administration - Richard Blum - Страница 52

Though the system may appear fine after an initial installation, it's wise to check. It may be tricky to understand everything you are looking at in this section, but reviewing this information will help as we cover these utilities and concepts in detail later in the book. Also, you can return to this section the next time you perform an Ubuntu distribution installation for guidance.

First, boot your Ubuntu Server VM. After the system has booted, log into the tty2 terminal, and do the following:

 Check for boot errors. There are three commands that can help you check for boot errors, and none of them requires the sudo command to run. The first is dmesg. This will display the kernel ring buffer, but that data is useful only if you check it soon after the system has booted.To see boot messages long after a system boot, type less /var/log/bootstrap.log at the prompt and press Enter. You can move forward through this log by pressing the spacebar. When you are done looking at the information, press the Q key to return to the command‐line prompt.Finally, you can look for boot errors and all kinds of messages via the journalctl command. To peruse this information, you will need to press the spacebar to move forward and then the Q key to quit your viewing.

 Determine the default boot level. The default boot level on a Linux system determines what applications are started when the system boots. The command to see this information is systemctl get‐default. It does not require the sudo command to use.Most likely, you will see graphical.target when you issue this command, meaning that if graphical user interface (GUI) software is available, the GUI will start on bootup. However, on Ubuntu Server, since GUI software is not installed by default, this response from the systemctl get‐default command does not indicate a GUI is provided.

 Check version information. Determining the version numbers of the system's main components is helpful when tracking down problems. First, make sure you have the right Ubuntu Server distribution version installed by typing cat /etc/issue at the prompt. The version is in the first few words of the displayed line.Check the Linux kernel version too. This is important to know because different features (and bugs!) exist in the various kernel versions. To see this information, you need to type uname ‐r at the command‐line prompt. You can also view this information via the cat /proc/version command.Finally, look at the version of the Bash shell running on the system. This is easy to accomplish with the bash ‐‐version command.

Once you've completed your checks, celebrate! You worked hard to get this Ubuntu Server distribution installed correctly.