Ubuntu linux 1

What information is displayed by dmesg? (Choose the most correct answer.)

o Only filesystem information o BIOS memory mapping @ All kernel hardware information o Memory allocation o Hardware networking information Explanation dmesg shows information about all the hardware controlled by the kernel. The listing includes information about the CPU, memory, disk drives, network cards, etc.

Which of the following devices represent a hotplug device?

o RAM (Random-access Memory) chips @ USB flash drives o CPU (Central Processing Unit) o PCI Express cards Explanation The USB flash drive represents a hotplug device. Hotplug devices can be removed while the computer is on. Linux uses software designed to detect these changes as the devices are added and removed. Hotplug devices also include FireWire devices. Coldplug devices should only be removed or replaced when the power to the computer is off. Attempting to remove these devices while the power is on can damage the computer. Coldplug devices include:

What does the telinit 5 command do?

o Removes all daemons from memory and powers the system off. @ Switches the system runlevel to multi-user graphical mode. o Switches the system runlevel to extended multi-user textual mode. o Allows only the root user to log in to the system. Explanation Telinit 5 (or init 5) switches the system runlevel to multi-user graphical mode. In multi-user graphical mode, the system provides the same capabilities as in extended user mode. However, the system also supports graphical log ins. Both the telinit and init commands can change the system runlevels. Telinit 0 removes all daemons from memory and powers the system off. Telinit 1 allows only the root user to log in to the system. Telinit 3 switches the system runlevel to multi-user textual mode with extended support for all network services.

Type the full device file name for the first partition on the hard drive with the third lowest ID number.

/dev/sdc1 /dev/sdc1 is the first partition (1) on the hard drive with the third lowest ID number (c). /dev/sdxn file names identify hard drives.

Which file includes a list of users who are able to shut down the system?

/ete/shutdown.allow o fete/down Explanation The /ete/shutdown.allow file has a list of users who can shut down the system. To use this file, edit /ete/inittab and include the shutdown -a line (-a indicates to use the file to determine who can shut down the system).

You have installed a new Linux system and you want to make a baseline of system performance. Which of these files contain baseline information? (Choose two.) /ps.aux /systat /meminfo o /epuinfo /top

/meminfo /epuinfo Explanation The cpuinfo and meminfo files located in the /proc directory should be recorded as part of a system baseline. Cpuinfo contains information about the CPU such as model, CPU speed, cache, etc. Meminfo contains information such as total memory, free memory, etc. Dmesg displays a snapshot of information about the hardware that is controlled by the kernel, and that output can be redirected to a file for use in system baseline documentation

The entry 3:2345:respawn:/sbin/mingetty tty3 exists in the /etc/inittab file for virtual terminal number 3. At what run levels is this virtual terminal available for access? all 2 through 5 none 3

2 through 5 Explanation The second field of each /etc/Inittab entry identifies the runlevels at which the process is available. In this case, the terminal is available in runlevels 2345.

You are experiencing a problem with one particular server. Each time it boots, it goes into single user mode even though no warnings or errors are reported. You want to verify that it is configured to boot to runlevel 3, just as all your other servers are. Which file would you check to find the default runlevel setting? /ete/re.d /ete/inittab fete/shadow /ete/profile

@ /ete/inittab Explanation The / ete/inittab file serves as the main configuration file for the init process/daemon (initialization or initial process or daemon). It contains configuration information for a number of startup settings such as the default runlevel. The /ete/profile file stores system-wide configuration commands and is used primarily to set environment variables. The re.d directory contains the daemon script files which run at boot and when the system switches runlevels. The fete/shadow file holds passwords and password expiration information for user accounts.

Which system component verifies the hardware and passes control of the computer to the boot loader?

@ BIOS o Init o CMOS o as kernel Explanation The BIOS is responsible for verifying system hardware, reading settings from the CMOS, detecting hardware changes, and passing control of the system to the boot loader.

Which daemon allows processes to communicate which each other and relay information about hotplug devices? hald D-Bus sysfs udev

@ D-Bus The Desktop Bus (D-Bus) daemon allows processes to communicate with each other and notify them of new hotplug devices. The Hardware Abstraction Layer (HAL) daemon (hald) provides all applications with data about current hardware. sysfs is a virtual file system mounted at /sys which exports information about hotplug devices so that other utilities can access the information. udev is a virtual file system that dynamically creates device files as devices are added and removed.

You have a Linux system that is configured to run in graphical multi-user mode by default. Before the system is started in the graphical multi-user mode, you need to perform some administrative tasks on the system. You need to boot the system to single-user mode. What should you do?

@ Provide a kernel boot option of 1. Explanation In this case, you should provide a kernel boot option of 1. Providing options to the kernel at boot time affect how the kernel is loaded. To change the runlevel, use the corresponding value in the kernel boot options area of the boot loader. You will not be able to edit the /etc/Inlttab file without first booting into the default runlevel specified in the /etc/Intttab file. Use the init= kernel option to change the initial process at boot time. For example, use init=/bin/bash to change the initial process to the Bourne-again shell (bash). Providing init=/bin/bash as a kernel option will allow you to view the /etc/tntttab file as read only. Use the CMOS settings to specify the boot sector containing the Master Boot Record (MBR).

You just installed a new CD-ROM drive in your computer. After boot, you can't find the CD-ROM drive anywhere. Where would be a good place to go to start troubleshooting?

@ Run dmesg. Explanation Run dmesg to troubleshoot hardware errors. This command shows the contents of the kernel ring buffer. It includes actions taken at startup, which would include configuring hardware devices. Run last to show the contents of the /var/Icq/wtmp file (in readable format). This shows all user logins. Run lastb to show the contents of the /var/loq/btrnp file (in readable format). This shows all failed login attempts. Run sar to view CPU statistics.

Which of the following has a process ID (PID) of 1?

@ The initial (init) process Explanation The initial (init) program gets the process ID (PID) of 1 because it's the first process to run on the system. The BIOS, boot loader, and OS kernel do not receive a PID.

You have made changes to the /ete/inittab file, but they do not seem to be taking effect. This is the busy time of day, and you do not want to bring the system down and back up. Which command forces the system to reread the entr is in the /ete/ inittab file?

@ init q Explanation The command init q will reread the entries in the /etc/Intttab file and make the settings active. The other choices given will change the status of the system: init 0 will change to shutdown mode, init 6 reboots the system, and init 1 changes to single-user mode.

You want to shut down the system immediately, but send a message to logged on users and allow running processes to close gracefully. Which command would you use?

@ shutdown -h now o shutdown -hk now o shutdown -s o shutdown -m now o shutdown -r Explanation Use the shutdown -h now command. The -h switch tells the system to halt (turn off). The now keyword means to start the process immediately. Regardless of the switches used, shutdown will notify users and will terminate processes gracefully. You must include a time parameter with the shutdown command or it will not work. -r reboots the system. -k sends a message that the system will shut down, but does not actually turn off the system (even if it is used with the-h switch).

You have informed users that you need to bring the machine down at the end of the day to perform routine maintenance. However, prior to shutting the system down, you want send a message to users and give them fifteen minutes to save data and exit the system. Which of the following commands should you use?

@) shutdown -h +15 It is time for a shutdown! Explanation Use shutdown -h +15 It is time for a shutdown! to send a message to logged-in users, wait 15 minutes, and shut down the system. Use shutdown -r to shut the system down immediately and reboot. Use halt or init 0 to shut the system down immediately without notification.

You just got a new input device, named GamePad, that you want to use on your computer. You don't think that the GamePad driver (i.e., kernel module) was compiled into the kernel of your Linux distribution. Which of the following commands will install the driver (gamepad.ko) into the kernel? (Select two.)

D depmod gamepad D insmod gamepad Explanation Use one of the following commands to install the gamepad.ko driver (i.e., kernel module) into the kernel: ##MARGINS=16,B,O,O##. insmod gamepad.ko installs modules into the kernel. The insmod command requires the full name of the module, including the .0 or .ko extension. ##MARGINS=16,O,O,O##. modprobe gamepad installs modules into the kernel. modprobe loads modules into the kernel along with any module dependencies. This utility also runs at startup to load modules into the kernel. depmod creates a file that lists module dependencies.

Which directory allows you to name devices when they are connected to the system? (Tip: Enter the full path to the directory.)

I/etc/udev/rules.d/ I Explanation Use the /etc/udev/rules.d/ directory to name devices. udev is a virtual file system that dynamically creates device files as devices are added and removed.

Which directory contains information about the system state and processes? (Tip: Enter the full path to the directory.)

I/proc I

Which directory contains information about each kernel module installed on the computer? (Tip: Enter the full path to the directory.)

I/sys/module Explanation The /sys/module has a sub-directory for each kernel module installed on the computer.

Which command displays information on all USB devices connected to the computer?

IISUSb I Explanation Isusb displays information on all USB devices connected to the computer. This utility uses the following options: ##MARGINS=16,B,O,O##. -v shows exhaustive information. ##MARGINS=16,O,O,O##. -s bus_name shows information for a specific bus.

Which of the following commands will display which boot options were given to the kernel at boot time? cat /proe/cmdline cat /proe/mounts cat /proe/modules cat /proe/version

cat /proe/cmdline Explanation Use cat /proe/cmdline command to display the boot options given to the kernel at boot time.

Which of the following commands would allow you to determine if a service or driver failed to load during boot up? (Choose all that apply.) o less /var/log/messages o dmesg o less /var/log/dmesg o less /var/log/secure

dmesg less /var/log/dmesg Explanation The command dmesg is used to view the contents of the /var/log/dmesg log file, which contains the output generated during the boot process. The /var/log/messages log file typically contains messages generated by system services, kernel events, and other general purpose logged events. The /var/log/secure typically is used to record authentication attempts.

Which of the following is the core process for Linux? x swapper init timer

init Explanation Init is the core process that spawns all other processes in a Linux operating system.

You need to perform some system maintenance, and want to prevent users from logging on while you do so. Which command should you run?

init 1 Explanation Run init 1 to put the system into single user mode and prevent additional logins. init 0 stops the system. init 6 reboots the system. There is no runlevel 7 (init 7).

You are trying to troubleshoot intermittent errors that are occurring while continuing to work on other projects. Which command displays system messages, but only the ones that are panic messages?

o mesg y o mesg @ dmesg -n 1 o dmesg Explanation Use the dmesg command to see error messages as they occur. Setting the level to number 1 (-n 1) only allows panic messages to be seen. The mesg utility differs from dmesg in that it does not show system calls, but rather allows (or disallows) other users to send you messages.