Chapter 23 Flashcards
Dealing with Linux Devices
Describe how Linux systems communicate with devices.
Linux systems create files in the /dev folder that applications use to send data to devices and retrieve data from devices. Device files can be either character files, which send and receive data one character at a time, or block files, which send and receive data in blocks.
Explain how you would find the hardware settings for a PCI board plugged into the Linux system.
The lspci command displays the PCI devices currently connected to the system. You can use that information with the lsdev command, which displays the interrupts, I/O ports, and DMA channels used by each device. You can also find that information in the /proc/interrupts, /proc/ioports, and /proc/dma files.
Explain how Linux can detect hot-pluggable devices.
The udev application runs in the background, monitoring the kernel ring buffer for new devices. When a new device is added, the udev application detects it from the kernel ring buffer messages and follows instructions defined in rules contained in the /etc/udev/rules.d directory.
What type of hardware interface uses interrupts, I/O ports, and DMA channels to communicate with the PC motherboard?
USB GPIO PCI Monitors Printers
C. PCI boards use interrupts, I/O ports, and DMA channels to send and receive data with the PC motherboard, so option C is correct. USB devices transmit data using a serial bus connected to the motherboard and don’t use DMA channels, so option A is incorrect. The GPIO interface uses memory-mapped specialty IC chips and not interrupts and I/O ports, so option B is incorrect. Monitors and printers are hardware devices and not hardware interfaces, so options D and E are incorrect.
What filesystem does the Linux system use to track ports used to communicate with PCI boards?
/proc/ioports /proc/interrupts /sys /dev /proc/dma
A. The Linux kernel uses the /proc/ioports file to track the I/O ports used by the installed PCI boards on the system, so option A is correct. The kernel uses the /proc/interrupts and /proc/dma files to track interrupts and the DMA channel, not I/O ports, so options B and E are incorrect. The /sys directory contains files used to track kernel, module, and system features, not I/O ports, so option C is incorrect. The /dev directory contains files used to transfer data to and from devices, not track their I/O ports, so option D is incorrect.
Where does Linux create files to send data to and receive data from directly with devices?
/sys /proc /etc /dev /dev/mapper
D. The kernel creates files in the /dev directory for each device on the Linux system. These files are used to send data to the device and read data from the device. Thus, option D is correct. The /sys and /proc directories are used by the kernel to display system information, not transfer data, so options A and B are incorrect. The /etc directory is used for configuration files, not for transferring data, so option C is incorrect. The /dev/mapper directory is used by virtual systems such as LVM and LUKS to create virtual files that indirectly interface with devices through another application, not directly, so option E is incorrect.
Katie Jane created a new LVM volume on her Linux system. Where in the virtual directory should she look to find the virtual file related to the new volume?
/dev /dev/mapper /proc /sys /etc
B. The kernel uses the /dev/mapper directory to create virtual files that interface with applications that manipulate data on a virtual LVM volume before being sent to a physical hard drive device, so option B is correct. The /dev directory contains the physical device files, not virtual files, so option A is incorrect. The kernel uses the /proc and /sys directories to display kernel and system information, not virtual files for LVM volumes, so options C and D are incorrect. The /etc directory contains configuration files for applications, not LVM volumes, so option E is incorrect.
Joel installed a new PCI card in his Linux system but is now getting a conflict with another device on the system. What command can he use to display the interrupts, I/O ports, and DMA channels in use by all the existing devices?
lsdev lsblk lspci lsusb dmesg
A. The lsdev command displays all the hardware information about all the devices connected to the system, so option A is correct. The lsblk command only displays information on block devices, so option B is incorrect. The lspci command only displays information about PCI devices, so option C is incorrect. The lsusb command only displays information about USB devices, so option D is incorrect. The dmesg command displays messages from the kernel ring buffer, not information about the current devices, so option E is incorrect.
Which Linux command displays the contents of the kernel ring buffer?
lsdev lsblk lspci lsusb dmesg
E. The dmesg command displays the kernel event messages contained in the kernel ring buffer, so option E is correct. The lsdev command displays hardware information about devices, but not messages from the kernel, so option A is incorrect. The lsblk command only displays information about block devices, not kernel event messages, so option B is incorrect. The lspci command only displays information about PCI devices, not kernel event messages, so option C is incorrect. The lsusb command only displays information about USB devices, not kernel event messages, so option D is incorrect.
Which software packages implement the X Windows graphical system in Linux? (Choose two.)
X.org CUPS Wayland X11 udev
A, C. The X.org and Wayland software packages implement the X Windows graphical system for Linux, so options A and C are correct. The CUPS software package implements PostScript printing for Linux, not X Windows graphical systems, so option B is incorrect. X11 is an X Windows standard but not a software package, so option D is incorrect. The udev program is used to detect hot-pluggable devices, not implement the X Windows graphical system, so option E is incorrect.
Sophia needs to connect her Linux system to a new network printer on the office network. What software package does she need to ensure is installed so she can configure the new network printer?
X.org CUPS Wayland X11 udev
B. The CUPS software package provides an interface to convert PostScript documents and send them to common printers, so option B is correct. The X.org and Wayland software packages are used to implement the X Windows graphical system in Linux, not interface with printers, so options A and C are incorrect. X11 is a standard for X Windows, not a software package for printers, so option D is incorrect. The udev program detects hot-pluggable devices but doesn’t interact directly with the printers, so option E is incorrect.
Which program runs in the background monitoring the kernel ring buffer messages for new devices?
X.org CUPS Wayland X11 udev
E. The udev program runs in the background and monitors the kernel ring buffer for event messages from new devices, so option E is correct. The X.org and Wayland software packages implement the X Windows graphical system but don’t listen for new devices, so options A and C are incorrect. The CUPS package interfaces with printers on the Linux system and doesn’t listen for new devices, so option B is incorrect. X11 is a standard for X Windows and not a software package that listens for new devices, so option D is incorrect.
Which program allows you to reload the defined rules for detecting and installing new devices?
udevadm udev lsusb lspci lsdev
A. The udevadm program allows you to send control messages to the udev application running in background, signaling it to reload the rules defined in the /etc/udev/rules.d directory, so option A is correct. The udev application can’t direct itself to reload the rules, so option B is incorrect. The lsusb, lspci, and lsdev programs are used for displaying hardware information for the system, not for directing the udev program to reload defined rules, so options C, D, and E are all incorrect.
