Linux LFCS Exam: True Statements about /dev/ with udev

True Statements about /dev/ with udev

Question

What of the following statements are true regarding /dev/ when using udev? (Choose TWO correct answers.)

Answers

Explanations

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A. B. C. D. E.

BD

B. Additional rules for udev can be created by adding them to /etc/udev/rules.d/. This statement is true. When using udev, additional rules can be created by adding them to /etc/udev/rules.d/. These rules can specify how udev should name devices, set permissions, and create symlinks, among other things. The rules are parsed in numeric order, so it's important to give them appropriate names to ensure that they are processed in the desired order.

D. The /dev/ directory is a filesystem of type tmpfs and is mounted by udev during system startup. This statement is true. The /dev/ directory is a special directory in the Linux filesystem that contains device files, which are used to interact with hardware devices. When using udev, the /dev/ directory is actually a filesystem of type tmpfs, which is a temporary filesystem that is stored in RAM. This means that the contents of /dev/ are not stored on disk, but are instead created dynamically by udev as devices are detected and configured.

A. Entries for all possible devices get created on boot even if those devices are not connected. This statement is false. When using udev, only entries for devices that are actually connected to the system are created in the /dev/ directory. This is in contrast to earlier versions of Linux, where entries for all possible devices were created at boot time, regardless of whether they were actually connected or not.

C. When using udev, it is not possible to create block or character devices in /dev/ using mknod. This statement is true. When using udev, device nodes are created dynamically as devices are detected and configured, so it is not necessary (or recommended) to manually create device nodes using mknod. In fact, attempting to create device nodes using mknod can interfere with udev's automatic device configuration and cause problems. Instead, additional rules for udev should be added to /etc/udev/rules.d/ to specify how devices should be named and configured.

E. The content of /dev/ is stored in /etc/udev/dev and is restored during system startup. This statement is false. There is no file or directory named /etc/udev/dev that stores the content of /dev/. As mentioned earlier, the contents of /dev/ are created dynamically by udev as devices are detected and configured, and are stored in a tmpfs filesystem.