101-500 Practice Exam Questions with Answers LPIC-1 Exam 101, Part 1 of 2, version 5.0 Certification

The correct command to change the ownership of file.txt to the user dan and the group staff is chown dan:staff file.txt. This command uses the colon (:) as a separator between the user and the group. The other options are incorrect because they use the wrong syntax or options for the chown command. Option A uses a slash (/) instead of a colon, which is not valid. Option C uses the -u and -g options, which are not supported by the chown command. Option D uses the -g option, which only changes the group, not the user. References:

[LPI Linux Essentials - 1.3 Basic File Management]

[LPI Linux Essentials - 2.1 Using Devices, Linux Filesystems, Filesystem Hierarchy Standard]

[LPI Linux Essentials - 2.2 Mounting, Unmounting Filesystems]

[LPI Linux Essentials - 2.3 Disk Partitions]

Chown Command in Linux: How to Change File Ownership - phoenixNAP

chown command in Linux with Examples - GeeksforGeeks

Chown Command in Linux: How to Use It - Help Desk Geek

Chown Command in Linux (File Ownership) | Linuxize

The command mount -a ensures that all file systems listed with the option auto in /etc/fstab are mounted. The /etc/fstab file contains the information about the file systems that can be mounted automatically or manually. The option auto means that the file system can be mounted automatically at boot time or when the command mount -a is issued. The option noauto means that the file system can only be mounted manually by specifying the device or mount point. The command mount -a ignores the file systems with the noauto option and mounts the rest of the file systems that are not already mounted. The other options are incorrect because they do not describe the correct behavior of the command mount -a. Option A is wrong because the command mount -a ignores the file systems with the noauto option. Option B is wrong because the command mount -a does not show any output, unless the -v option is used. To show the mounted file systems, the command mount without any arguments can be used. Option C is wrong because the command mount -a does not open any editor. To edit the /etc/fstab file, a text editor such as vi, nano, or gedit can be used. Option E is wrong because the command mount -a does not mount all file systems listed in /etc/fstab, but only those with the auto option. References:

[LPI Linux Essentials - 2.2 Mounting, Unmounting Filesystems]

Linux mount Command with Examples - phoenixNAP

How does the Linux command “mount -a” work? - Unix & Linux Stack Exchange

mount command in Linux with Examples - GeeksforGeeks

mount???????????????Linux??????

The statement that is correct for a command line ending with a & character is that the command is run in background of the current shell. The & character tells the shell to run the command in the background, which means that the shell does not wait for the command to finish and returns the prompt immediately. The command’s output is not redirected to /dev/null, unless explicitly specified. The result of the command does not define if the next command will be run, unless the commands are separated by a logical operator such as && or ||. The command is not run as a direct child of the init process, unless the shell is the init process itself. References: [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.1: Work on the command line, Background Processes

The PATH variable defines the directories in which a Bash shell searches for executable commands. The PATH variable is a colon-separated list of directories that the shell scans when a command is entered. For example, if the PATH variable is set to /usr/local/bin:/usr/bin:/bin, then the shell will look for the command in these three directories, in order. If the command is not found in any of these directories, the shell will report an error message. The other options are either invalid or do not perform the desired task. The BASHEXEC, EXECPATH and PATHRC variables are not valid Bash variables. The BASHRC variable is used to specify a file that is executed whenever a new interactive shell is started, but it does not affect the command search path. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.1 Work on the command line

LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)

The correct answer is A, tr -d ‘\r’ < userlist.txt > newlist.txt. This command will use the tr utility to delete the carriage return characters (\r) from the userlist.txt file and redirect the output to the newlist.txt file. The tr utility is used to translate, delete, or squeeze characters from the standard input and write the result to the standard output. The syntax of the tr command is:

tr [options] set1 [set2]

The options can modify the behavior of the tr command, such as complementing, squeezing, or truncating the sets of characters. The set1 and set2 are strings of characters that specify the translation to be performed. The characters in set1 are replaced by the corresponding characters in set2. If set2 is omitted, the characters in set1 are deleted.

The -d option tells tr to delete the characters in set1 from the output. The \r character is a special escape sequence that represents the carriage return character, which is used in Windows systems to mark the end of a line, along with the line feed character (\n). The < and > symbols are redirection operators that redirect the input and output of a command to a file or device. The < symbol redirects the standard input of a command from a file, while the > symbol redirects the standard output of a command to a file, overwriting any existing content.

Therefore, the command tr -d ‘\r’ < userlist.txt > newlist.txt will read each character from the userlist.txt file, delete any carriage return characters, and write the output to the newlist.txt file. This will effectively change all CR-LF line breaks (\r\n) in the userlist.txt file to Linux standard LF line breaks (\n) and store the result in newlist.txt.

The other commands are incorrect for the following reasons:

B, tr -c ‘\n\r’ ‘’ userlist.txt: This command will not work as expected, because it has several errors. First, the -c option tells tr to complement the set of characters in set1, which means that the operations will apply to the characters that are not in the set1. However, the set1 in this command is ‘\n\r’, which includes both the line feed and the carriage return characters, so the complement will be all the other characters except these two. Second, the set2 in this command is an empty string (‘’), which means that tr will delete the characters that match the set1 (or its complement, in this case). Third, the redirection operators are reversed, which means that tr will read the input from the newlist.txt file and write the output to the userlist.txt file, instead of the other way around. Therefore, the command tr -c ‘\n\r’ ‘’ userlist.txt will delete all the characters except the line feed and the carriage return characters from the newlist.txt file and overwrite the userlist.txt file with the output, which will be a series of blank lines.

C, tr ‘\r\n’ ‘’ newlist.txt: This command will not work as expected, because it has several errors. First, the set1 in this command is ‘\r\n’, which means that tr will match the carriage return and the line feed characters separately, not as a pair. Second, the set2 in this command is an empty string (‘’), which means that tr will delete the characters that match the set1. Third, the redirection operators are missing, which means that tr will not read the input from the userlist.txt file or write the output to the newlist.txt file, but instead it will expect the input from the standard input and write the output to the standard output. Therefore, the command tr ‘\r\n’ ‘’ newlist.txt will delete all the carriage return and the line feed characters from the standard input and write the output to the standard output, and treat the userlist.txt and newlist.txt as additional arguments that will cause an error.

D, tr ‘\r’ ‘\n’ userlist.txt newlist.txt: This command will not work as expected, because it has several errors. First, the set1 and set2 in this command are ‘\r’ and ‘\n’, which means that tr will replace the carriage return characters with the line feed characters, not delete them. Second, the redirection operators are missing, which means that tr will not read the input from the userlist.txt file or write the output to the newlist.txt file, but instead it will expect the input from the standard input and write the output to the standard output. Third, the userlist.txt and newlist.txt are treated as additional arguments that will cause an error. Therefore, the command tr ‘\r’ ‘\n’ userlist.txt newlist.txt will replace all the carriage return characters with the line feed characters from the standard input and write the output to the standard output, and report an error for the extra arguments.

E, tr -s ‘/M/J/’ userlist.txt newlist.txt: This command will not work as expected, because it has several errors. First, the -s option tells tr to squeeze the repeated characters in set1 with a single occurrence, not delete them. Second, the set1 in this command is ‘/M/J/’, which is not a valid escape sequence for the carriage return and the line feed characters. The correct escape sequences are ‘\r’ and ‘\n’, respectively. Third, the redirection operators are missing, which means that tr will not read the input from the userlist.txt file or write the output to the newlist.txt file, but instead it will expect the input from the standard input and write the output to the standard output. Fourth, the userlist.txt and newlist.txt are treated as additional arguments that will cause an error. Therefore, the command tr -s ‘/M/J/’ userlist.txt newlist.txt will squeeze the repeated occurrences of the characters /, ^, M, and J from the standard input and write the output to the standard output, and report an error for the extra arguments.

 When using rpm --verify to check files created during the installation of RPM packages, the following information is taken into consideration:

Timestamps. RPM compares the modification time of the installed files with the original time stored in the RPM database. If the file has been modified after installation, the timestamp will differ and RPM will report it with an M flag1.

MD5 checksums. RPM calculates the MD5 checksum of the installed files and compares it with the original checksum stored in the RPM database. If the file has been altered in any way, the checksum will differ and RPM will report it with an 5 flag1.

File sizes. RPM compares the size of the installed files with the original size stored in the RPM database. If the file has been truncated or appended, the size will differ and RPM will report it with an S flag1.

RPM does not take into consideration the following information:

Inodes. RPM does not check the inode number of the installed files, as it is not a reliable indicator of file identity. The inode number can change if the file is moved, copied, or restored from a backup2.

GnuPG signatures. RPM does not verify the GnuPG signatures of the installed files, as they are not part of the RPM package format. The GnuPG signatures are used to verify the authenticity and integrity of the RPM package files before installation, not after3.

The p command in vi inserts the content of the buffer below the current line. The buffer is where the deleted or yanked text is stored temporarily. The P command inserts the buffer above the current line. The i command enters the insert mode before the cursor position. The U command restores the current line to its original state. The u command undoes the last change made to the file. References:

[LPI Linux Essentials - 1.3 Basic Editing]

[LPI Linux Essentials - 1.4 I/O Redirection]

[LPI Linux Essentials - 1.5 Manage Simple Partitions and Filesystems]

The command dd can be used to create a USB storage media from a disk image. The command dd is a low-level utility that can copy and convert data from one source to another, such as files, devices, or pipes. It can be used to create a bootable USB drive from an ISO image or a raw disk image. The syntax is: dd if=input of=output [options]. For example, to create a USB storage media from a disk image file named linux.img, the command would be:

dd if=linux.img of=/dev/sdb

This will copy the contents of linux.img to the device /dev/sdb, which is assumed to be the USB drive. The device name may vary depending on the system, so it is important to check the correct device name before running the command. The command dd can also accept various options, such as bs to specify the block size, status to show the progress, or conv to apply conversions to the data. For example, to create a USB storage media from an ISO image file named linux.iso, with a block size of 4 MB and a progress indicator, the command would be:

dd if=linux.iso of=/dev/sdb bs=4M status=progress

The command dd is also known as "disk destroyer" because it can overwrite data without warning or confirmation. Therefore, it is advisable to use it with caution and backup any important data before using it. The other options are not correct because:

gdisk is a command to create and manipulate GUID partition tables (GPT), but it does not create a USB storage media from a disk image1.

cc is a command to compile C programs, but it does not create a USB storage media from a disk image2.

fdisk is a command to create and manipulate DOS partition tables, but it does not create a USB storage media from a disk image3.

mount is a command to mount file systems, but it does not create a USB storage media from a disk image4. References:

How to Create a Bootable Linux USB Flash Drive, the Easy Way

dd(1) — Linux manual page

How to use the dd command in Linux - TechRepublic

LPI Exam 101 Detailed Objectives, section 1.101.3

The first program that is usually started, at boot time, by the Linux kernel when using SysV init is /sbin/init. This program is responsible for reading the /etc/inittab file and executing the appropriate scripts and programs for each runlevel. The other options are not valid programs that are started by the kernel. /lib/init.so is a shared library that is used by some init programs, but not by SysV init. /etc/rc.d/rcinit is a script that is run by init, not by the kernel. /proc/sys/kernel/init is a kernel parameter that can be used to specify a different init program, but the default value is /sbin/init. /boot/init is not a standard location for an init program, and it is unlikely that the kernel would find it there. References:

1: SysVinit - ArchWiki

2: Linux: How to write a System V init script to start, stop, and restart my own application or service - nixCraft

3: sysvinit - Gentoo wiki

 The command dmesg will display messages from the kernel that were output during the normal boot sequence. The dmesg command reads the kernel ring buffer, which is a data structure that stores the most recent messages generated by the kernel. The dmesg command can also be used to display messages from the kernel that were output after the boot sequence, such as hardware events, driver messages, or system errors. The dmesg command has various options to filter, format, or save the output. For example, dmesg -T will display human-readable timestamps for each message, and dmesg -w will display the messages in real time as they occur. References:

1: How to view all boot messages in Linux after booting? - Super User

2: dmesg(1) - Linux manual page

3: Kernel ring buffer - Wikipedia

The commands init 1 and telinit 1 both bring a system running SysV init into a state in which it is safe to perform maintenance tasks. This state is also known as single-user mode or runlevel 1, where only the root user can log in and no network services are running. The command shutdown -R 1 now is incorrect, because it reboots the system instead of entering single-user mode. The command shutdown -single now is invalid, because the -single option does not exist for the shutdown command. The command runlevel 1 is also invalid, because runlevel is a command that displays the current and previous runlevels, not a command that changes the runlevel. References:

1: SysVinit - ArchWiki

2: Linux: How to write a System V init script to start, stop, and restart my own application or service - nixCraft

3: sysvinit - Gentoo wiki

The file in the /proc filesystem that lists the parameters passed from the bootloader to the kernel is /proc/cmdline. This file contains a single line of text that shows the command line arguments that were used to boot the kernel. These arguments can include various options, such as the root device, the init process, the console device, and more. The /proc/cmdline file is read-only and cannot be modified at runtime. The parameters in this file are determined by the bootloader configuration, such as GRUB or LILO, and can be changed by editing the corresponding files12.

The file that you should check within the /proc tree to learn which IRQs are being used by which kernel drivers is /proc/interrupts1 Comprehensive Explanation: The /proc/interrupts file is a virtual file that provides information about the number and type of interrupts per CPU per I/O device12. It displays the IRQ number, the number of that interrupt handled by each CPU core, the interrupt type, and a comma-delimited list of drivers that are registered to receive that interrupt12. For example, the following output shows the contents of /proc/interrupts on a system with two CPUs and several devices:

The first column shows the IRQ number, followed by one column for each CPU core showing the number of interrupts handled by that core. The last column shows the interrupt type and the driver name. Some interrupt types are:

IO-APIC-edge: An edge-triggered interrupt from the I/O Advanced Programmable Interrupt Controller (APIC), which is a hardware device that handles and distributes interrupts.

IO-APIC-fasteoi: A fast end-of-interrupt from the I/O APIC, which means that the interrupt is acknowledged early to allow nesting interrupts.

PCI-MSI-edge: A Message Signaled Interrupt (MSI) from the Peripheral Component Interconnect (PCI) bus, which is a hardware bus that connects devices to the system. MSI is a method of sending interrupts using special messages instead of dedicated lines.

NMI: A Non-Maskable Interrupt, which is a hardware interrupt that cannot be ignored by the CPU and usually indicates a critical error.

LOC: A Local timer interrupt, which is a periodic interrupt generated by a local APIC on each CPU core for scheduling purposes.

RES: A Rescheduling interrupt, which is a type of inter-processor interrupt (IPI) that is sent to a CPU core to force it to reschedule its current task.

To check if a new ethernet card might be conflicting with another device, you can look for the driver name of the ethernet card in the /proc/interrupts file and see if it shares the same IRQ number with another device. If so, you can try to change the IRQ assignment of the devices or use the smp_affinity file to control which CPU cores can handle the interrupt12.

 The BIOS (Basic Input/Output System) is a firmware that is stored in a ROM chip on the motherboard and is responsible for initializing the hardware and loading the bootloader. The BIOS has a setup utility that allows the user to configure various settings, such as the boot device order, the hardware configuration, the system date and time, the security options, etc. The BIOS does not store information about the Linux kernel version, the time zone, or the system’s hostname, as these are part of the operating system and are not relevant for the BIOS. References: LPI Linux Essentials - 1.101.1, LPI Linux Administrator - 102.1

The shutdown command is used to bring the system down in a safe and controlled way. It can take various options and arguments, such as the time of shutdown, the message to broadcast to users, the halt or reboot mode, etc. The option -r instructs the shutdown command to reboot the system after shutting down. The argument now means to shut down immediately. Therefore, shutdown -r now will reboot the system without delay. The telinit command is used to change the run level of the system. It takes a single argument that specifies the new run level. The run level 6 is reserved for rebooting the system. Therefore, telinit 6 will also reboot the system. The other options are either incorrect or irrelevant. shutdown -r “rebooting” will also reboot the system, but with a delay of one minute and a message to the users. telinit 0 will halt the system, not reboot it. shutdown -k now “rebooting” will only send a warning message to the users, but not actually shut down or reboot the system. References: LPI Linux Essentials - 1.101.2, LPI Linux Administrator - 101.3

 udev is a device manager that dynamically creates and removes device nodes in the /dev/ directory. It also handles device events, such as adding, removing, or changing the attributes of devices. udev uses rules to match devices and assign properties, permissions, names, symlinks, and other actions. The rules are stored in files under /lib/udev/rules.d/ and /etc/udev/rules.d/. The latter directory can be used to create additional or override existing rules. The /dev/ directory is not a regular directory on the root filesystem, but a virtual filesystem of type tmpfs that is mounted by udev during system startup. tmpfs is a filesystem that resides in memory and can grow and shrink dynamically. The content of /dev/ is not stored in /etc/udev/dev, but is created by udev based on the rules and the available devices. udev does not prevent the creation of block or character devices in /dev/ using mknod, but it may overwrite or remove them if they conflict with the rules or the device events. References: LPI Linux Essentials - 1.101.2, LPI Linux Administrator - 102.4

The quiet kernel parameter instructs the kernel to suppress most boot messages, except for critical errors12. The quiet parameter can be added to the GRUB_CMDLINE_LINUX_DEFAULT variable in the /etc/default/grub file and then run sudo update-grub to apply the changes3. The quiet parameter can also be used in combination with other parameters, such as splash, to enable a graphical boot screen4.

The other options in the question are not valid or do not have the same functionality as the quiet parameter:

silent: There is no such kernel parameter in Linux.

verbose=0: This parameter is used to set the verbosity level of the kernel messages, but it does not suppress them completely. The valid values for this parameter are from 0 (quiet) to 7 (debug)5.

nomesg: This parameter is used to disable all kernel messages on the console, including the emergency ones. This parameter is not recommended for normal use, as it can hide critical errors and prevent troubleshooting.

 Run levels are predefined modes of operation in the SysV init system that determine which processes and services are started or stopped. The default run level is the one that the system enters after booting. It is usually specified in the /etc/inittab file with a line like id:5:initdefault:. The run levels 0 and 6 should never be declared as the default run level because they are used to halt and reboot the system, respectively. If they are set as the default, the system will enter an endless loop of shutting down and restarting. The other run levels (1-5) have different meanings depending on the distribution, but they usually correspond to single-user mode, multi-user mode, network mode, graphical mode, etc. References: LPI Linux Essentials - 1.101.2, LPI Linux Administrator - 101.3

The program that is run after the BIOS completes its tasks is the bootloader12. The bootloader is a small program that loads the operating system into memory and executes it. The bootloader can be located in the Master Boot Record (MBR) of the first hard disk or the boot sector of a partition for BIOS systems, or in an .efi file on the EFI System Partition for UEFI systems12. The bootloader can also display a menu to allow the user to choose from different operating systems or kernel versions to boot12.

The other options in the question are not correct because:

B. The inetd program: This is a program that listens for incoming network connections and launches the appropriate service for them. It is not involved in the boot process3.

C. The init program: This is a program that is executed by the kernel as the first user-space process. It is responsible for starting and managing other processes and services. It is not run by the BIOS.

D. The kernel: This is the core of the operating system that controls everything in the system. It is loaded and executed by the bootloader, not by the BIOS.

The /etc/inittab file is used by the SysV init system to configure the behavior of different runlevels and the actions to be taken when certain events occur. One of the events that can be configured is the ctrl-alt-delete key combination, which by default triggers a system reboot. To disable this feature, the /etc/inittab file should be modified to comment out or remove the line that starts with ca::ctrlaltdel:. References: LPI Linux Essentials - 1.101.2, LPI Linux Administrator - 101.1

The /proc/ directory is a virtual filesystem that provides a view of the kernel’s data structures and parameters. It contains information about processes, hardware, memory, modules, and other aspects of the system. The files in /proc/ are not stored on disk, but are generated on the fly by the kernel when they are accessed. Therefore, any changes to files in /proc/ are immediately recognized by the kernel and affect its behavior. For example, writing a value to /proc/sys/kernel/hostname will change the system’s hostname without rebooting. The files in /proc/ are not all read-only; some of them can be modified by the root user or by processes with the appropriate permissions. The files in /proc/ are readable by any user, unless restricted by the kernel or by the mount options. References: LPI Linux Essentials - 1.101.2, LPI Linux Administrator - 102.3

The lspci command can display information about the system hardware, such as:

Device IRQ settings1: The lspci command can show the interrupt request (IRQ) number assigned to each device by using the -v option. The IRQ number indicates how the device communicates with the CPU.

PCI bus speed2: The lspci command can show the speed of the PCI bus by using the -vv option. The speed is expressed in megahertz (MHz) or gigahertz (GHz) and indicates how fast the data can be transferred between the device and the bus.

Device vendor identification3: The lspci command can show the name and identification number of the device vendor by using the -n or -nn option. The vendor identification helps to identify the manufacturer and model of the device.

systemd, Upstart, and SysV init are all init systems used within Linux systems. An init system is the first process executed by the kernel at boot time, which has a process ID (PID) of 1, and is responsible for starting and managing all other processes on the system. Different init systems have different features, advantages, and disadvantages. Some of the most common init systems are:

systemd: A relatively new and modern init system that aims to provide a unified and efficient way of managing system and service states. It is compatible with SysV and LSB init scripts, and supports features such as parallel processing, socket activation, logging, job scheduling, and more. It is the default init system for many popular Linux distributions, such as Fedora, Debian, Ubuntu, Arch Linux, and others12.

Upstart: An event-based init system developed by Ubuntu as a replacement for SysV init. It starts and stops system tasks and processes based on events, such as hardware changes, network availability, filesystem mounting, etc. It is a hybrid init system that uses both SysV and systemd scripts, and supports features such as parallel processing, dependency tracking, logging, and more. It is the default init system for some older versions of Ubuntu, and some other Linux distributions, such as Linux Mint and Chrome OS12.

SysV init: A mature and traditional init system that follows the System V (SysV) design of Unix operating systems. It uses a series of runlevels to define the state of the system, and executes scripts in the /etc/rc.d or /etc/init.d directories according to the current runlevel. It is simple and stable, but lacks some features of modern init systems, such as parallel processing, event handling, dependency tracking, etc. It is still used by some Linux distributions, such as Slackware, Gentoo, and others12.

The bg command is used to resume a suspended command in the background, allowing it to run without user interaction. The command takes a job ID as an argument, which can be obtained by using the jobs command. Alternatively, if no job ID is specified, bg will resume the most recently suspended job. The bg command is part of the job control features of the Linux shell, which allow users to manage multiple processes running in the same terminal. References:

LPI Linux Essentials: 1.3.2 Job Control

LPI Linux Administrator: 103.1 Work on the command line

The ? symbol within regular expressions represents an optional match of the preceding qualifier. A qualifier is a character or a group of characters that can be repeated a certain number of times, such as , +, ?, {n}, {n,}, or {n,m}. The ? symbol means that the qualifier can occur zero or one times, but not more. For example, the regular expression colou?r matches both “color” and “colour”, but not “colouur” or “colr”. The ? symbol can also be used to make other qualifiers lazy, meaning that they will match the smallest possible number of characters, instead of the largest (greedy). For example, the regular expression a.?b matches the shortest string that starts with “a” and ends with “b”, such as “ab” or “a-b”, but not “a-b-c”. References:

[LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.7: Perform basic file management, Weight: 4, Key Knowledge Areas: Use of egrep to search for extended regular expressions in text output.

[Regular expression syntax cheat sheet], Topic: Quantifiers.

The export command is a Bash built-in command that exports environment variables and functions for use in other shell sessions1. Environment variables are named values that affect the behavior of applications and processes2. For example, the PATH variable stores a list of directories where executable programs are located, and the LANG variable sets the language and locale of the system2. By using the export command, you can make these variables available to any child process spawned by the current shell1. For example, if you want to set the EDITOR variable to vim for all subshells, you can run:

export EDITOR=vim

The export command can also be used to export functions, which are blocks of code that can be reused by invoking their name3. For example, if you want to create and export a function that prints “Hello world”, you can run:

hello () { echo “Hello world”; } export -f hello

Then, you can call the hello function in any subshell or script that inherits the environment from the current shell.

The other options are not related to the export command. Option A refers to the mount command, which attaches a filesystem to a directory4. Option B refers to the command substitution feature, which runs a command in a subshell and replaces it with its output5. Option C refers to the history command, which displays the command history of the current shell. Option E refers to the exportfs command, which maintains the table of exported NFS shares.

The << character is used to create a here document, which is a special type of redirection that reads input from the current source until a line containing only the delimiter (with no trailing blanks) is seen. The delimiter is specified after the << operator, and can be any string. For example, the following command will print everything between the << EOF and EOF lines:

cat << EOF This is a here document It can span multiple lines EOF

The output is:

This is a here document It can span multiple lines

The < character is used for normal input redirection, which reads data from a file or another command. The <| and !< characters are not valid redirection operators in Linux. The &< character is used to duplicate input file descriptors, which is an advanced topic not covered by the Linux Essentials exam. References:

[LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.4: Use streams, pipes and redirects, Weight: 4, Key Knowledge Areas: Redirecting standard input, standard output and standard error.

[LPI Linux Essentials Certification All-in-One Exam Guide], Chapter 5: Working with Files, Page 167, Using Here Documents.

QUESTIONNO: 16

Which of the following commands will NOT update the modify timestamp on the file /tmp/myfile.txt?

A. file /tmp/myfile.txt

B. echo "Hello" >/tmp/myfile.txt

C. sed -ie "s/1/2/" /tmp/myfile.txt

D. echo -n "Hello" >>/tmp/myfile.txt

E. touch/tmp/myfile.txt

Answer: A

The file command will not update the modify timestamp on the file /tmp/myfile.txt because it only reads the file content and determines its type. It does not write or change anything in the file.

The other commands will update the modify timestamp on the file /tmp/myfile.txt because they either overwrite the file content (B and C), append to the file content (D), or explicitly change the file timestamp (E).

 The dpkg-reconfigure command is used to reconfigure an already installed package. It asks configuration questions for the package, just as if the package were being installed for the first time. This can be useful if the user wants to change some settings or options for the package without reinstalling it. The dpkg-reconfigure command can also be used to fix a broken package configuration or to restore the default settings. References:

dpkg-reconfigure(8) - Linux man page

Linux Professional Institute: Exam 101 Objectives

The command that searches for packages owning the file /etc/debian_version is dpkg –S /etc/debian_version. The dpkg command is the low-level tool for installing, removing, configuring, and querying Debian packages. The -S or --search option takes a file name or a pattern as an argument and searches for the packages that contain the matching files. The output shows the package name and the file name separated by a colon. For example, running dpkg -S /etc/debian_version will produce the output base-files:/etc/debian_version, indicating that the file /etc/debian_version belongs to the base-files package. The other commands are either invalid or do not perform the desired task. The apt-get command is used to download and install packages from the Debian repositories, but it does not have a search option. The apt command is a high-level tool for managing packages, but it does not have a -r option. The find command is used to search for files in the file system, but it does not have a -dpkg option. The apt-file command is used to search for files in the packages available in the Debian repositories, but it requires a subcommand such as search or show before the file name or pattern. References:

Linux Essentials - Linux Professional Institute Certification Programs1

Exam 101 Objectives - Linux Professional Institute2

dpkg(1) - Linux manual page3

apt-get(8) - Linux manual page

apt(8) - Linux manual page

find(1) - Linux manual page

apt-file(1) - Linux manual page

In Bash, inserting 1>&2 after a command redirects standard output to standard error. This means that the output of the command that normally goes to the standard output stream (file descriptor 1) will be sent to the standard error stream (file descriptor 2) instead. This can be useful if we want to capture or discard both the normal output and the error output of a command. For example, if we want to run a command and send both its output and error to /dev/null (a special device that discards any data written to it), we can use:

command > /dev/null 1>&2

This will redirect the standard output of command to /dev/null, and then redirect the standard error of command to the same place as the standard output, which is /dev/null. The other options are not correct because:

A. standard error to standard input: This is not possible, because standard input is a read-only stream, and we cannot redirect output to it.

B. standard input to standard error: This is not what 1>&2 does, because 1 refers to standard output, not standard input. To redirect standard input to standard error, we would need to use 0>&2, where 0 refers to standard input.

D. standard error to standard output: This is not what 1>&2 does, because it would require the opposite order of file descriptors: 2>&1. This would redirect standard error to standard output, not the other way around.

E. standard output to standard input: This is not possible, for the same reason as option A. References:

Bash redirections cheat sheet

How to redirect stderr to a file - Linuxize

The cut command is used to extract sections from each line of a file or input stream. The -d option specifies the delimiter that separates the fields in each line. The -f option specifies the fields to select. In this case, the delimiter is a colon (:) and the fields are 1 and 7. The first field is the user name and the seventh field is the login shell. Therefore, the cut command with these options will generate a list of user names and their login shells from /etc/passwd. References:

Linux cut Command Explained with 6 Examples

How to Use the Linux cut Command

cut command in Linux with examples

 The output of the given command line is foo bar. The command line consists of three commands that are connected by pipes (|). A pipe is a symbol that redirects the standard output of one command to the standard input of another command. The echo command prints its argument to the standard output, which is foo bar in this case. The tee command reads from the standard input and writes to both the standard output and a file. The file name is given as an argument, which is bar in this case. The cat command reads from the standard input and writes to the standard output. Therefore, the command line does the following:

The echo command prints foo bar to the standard output, which is redirected to the standard input of the tee command by the first pipe.

The tee command reads foo bar from the standard input and writes it to both the standard output and the file bar. The standard output of the tee command is redirected to the standard input of the cat command by the second pipe.

The cat command reads foo bar from the standard input and writes it to the standard output, which is displayed on the terminal.

Hence, the output of the command line is foo bar. The other options are either incorrect or not applicable. The cat, tee bar and bar are not printed by any of the commands. The foo is only part of the output, not the whole output. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.4 Use streams, pipes and redirects

LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)

The -v option for the egrep command activates the invert matching mode, which means that it only outputs the lines that do not match the given pattern or regular expression. This is useful for filtering out unwanted lines or finding exceptions in a file. For example, the following command will output all the lines in the file my_text that do not contain the word “Linux”:

egrep -v Linux my_text

The -v option can be combined with other options to modify the output format or behavior of the egrep command. For example, the -c option will count the number of non-matching lines instead of printing them, and the -i option will ignore the case of the pattern while matching. References:

[LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.7: Perform basic file management, Weight: 4, Key Knowledge Areas: Use of egrep to search for extended regular expressions in text output.

[Linux egrep Command with Examples], Topic: Invert Matching with egrep.

The correct command to change the number of days before the ext3 filesystem on /dev/sda1 has to run through a full filesystem check while booting is tune2fs -i 200 /dev/sda1. This command sets the interval between two filesystem checks to 200 days. The tune2fs command allows you to view and change various filesystem parameters on Linux ext2, ext3, or ext4 filesystems. The -i option specifies the time interval between checks. The other options are incorrect because they use the wrong parameters for the tune2fs command. Option A is wrong because the -d option is not supported by the tune2fs command. Option B is wrong because the -c option sets the maximum number of mounts, not days, before a check. Option D is wrong because the -n option is not supported by the tune2fs command. Option E is wrong because the --days option is not supported by the tune2fs command. References:

[LPI Linux Essentials - 2.2 Mounting, Unmounting Filesystems]

15 tune2fs command examples in Linux [Cheat Sheet] - GoLinuxCloud

Linux tune2fs command With Examples - GeeksforGeeks

tune2fs command-file system management - Linuxstar

tune2fs Command Examples - Gianforte School of Computing

The uptime and top commands can be used to determine how long the system has been running. The uptime command displays the current time, the system load, the number of users logged in, and the time since the system was last booted. The top command displays information about the processes running on the system, as well as the system load, the number of users logged in, and the time since the system was last booted. The other options are either invalid or do not perform the desired task. The up command is not a valid Linux command. The uname -u command displays the user ID of the current user, not the system uptime. The time –up command is not a valid syntax for the time command, which measures the execution time of a command, not the system uptime. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.2 Process management

LPIC-1 Linux Administrator 101-500 Exam FAQ, LPIC-1 Exam 101 Objectives, GNU and Unix Commands (Total Weight: 25)

The df command is used to report the disk space usage of the filesystems on a Linux system. The -i option is used to display the inode usage of each mounted filesystem. An inode is a data structure that stores the metadata of a file or directory, such as its size, owner, permissions, etc. Each filesystem has a fixed number of inodes, which limits the number of files and directories that can be created on it. The df -i command shows the total number of inodes, the number of used and free inodes, and the percentage of inode usage for each filesystem. For example:

[tcarrigan@rhel ~]$ df -i Filesystem Inodes IUsed IFree IUse% Mounted on /dev/sda2 1310720 83167 1227553 7% / devtmpfs 249974 386 249588 1% /dev tmpfs 251374 1 251373 1% /dev/shm tmpfs 251374 570 250804 1% /run tmpfs 251374 16 251358 1% /sys/fs/cgroup /dev/sda1 524288 312 523976 1% /boot tmpfs 251374 1 251373 1% /run/user/1000

The other options are not valid commands or options. The du command is used to estimate the disk usage of files and directories, but it does not have an -i option. The lsfs and printfs commands do not exist on a standard Linux system. References:

Inodes and the Linux filesystem | Enable Sysadmin

filesystems - Find where inodes are being used - Unix & Linux Stack …

filesystems - How much space does an inode occupy? - Unix & Linux Stack …

The cut command is used to extract selected portions of each line of a file or a stream. The -f option is used to specify the fields to be extracted, separated by commas. The -d option is used to specify the delimiter that separates the fields. The default delimiter is the tab character. The cut command can only select output by field position, not by field content. The cut command can also work on non-ASCII text, such as UTF-8 encoded text. The cut command can use different input and output delimiters, but only if the output delimiter is specified by the --output-delimiter option. The cut command cannot reorder fields, meaning that the output fields will always appear in the same order as the input fields. To reorder fields, other commands such as awk or sed can be used. References:

LPI 101-500 Exam Objectives, Topic 103.7, Weight 4

LPI Learning Materials, Chapter 3.7, Basic Scripting

Web Search Results, 

The former path of the data can be kept intact by creating a symbolic link from the old to the new path of the data or by mounting the new filesystem on the original path of the data. A symbolic link is a special file that points to another file or directory. It can be used to create a shortcut to the new location of the data without changing the applications that access it. Mounting the new filesystem on the original path of the data means that the data will appear as if it is still in the same location, but it is actually stored on a different device or partition. This can be done by editing the /etc/fstab file or using the mount command. References:

[LPI Linux Essentials - 1.3 Basic File Management]

[LPI Linux Essentials - 1.4 Finding Files]

[LPI Linux Essentials - 2.1 Using Devices, Linux Filesystems, Filesystem Hierarchy Standard]

[LPI Linux Essentials - 2.2 Mounting, Unmounting Filesystems]

[LPI Linux Essentials - 2.3 Disk Partitions]

 The vi editor is a text editor that operates in two modes: command mode and insert mode. In command mode, the user can enter commands to perform various operations on the text, such as copying, pasting, deleting, moving, searching, etc. In insert mode, the user can type text into the file. To switch from command mode to insert mode, the user can press i, a, o, or other keys. To switch from insert mode to command mode, the user can press Esc. The yy command is used to copy (yank) the current line into a buffer. The number before the yy command specifies how many lines to copy, starting from the current line. Therefore, the command 17yy will copy the current line and the following 16 lines (17 lines total) into a buffer. The buffer can then be pasted into another location by using the p or P command. Note that the command 17yy does not paste the copied lines, it only copies them. References:

LPI 101-500 Exam Objectives, Topic 103.8, Weight 4

LPI Learning Materials, Chapter 3.8, Advanced Scripting

Web Search Results, 1

The dd command can be used to create a new file that is 100kB in size. The dd command copies data from one source to another, using specified input and output block sizes. To create a new file that is 100kB in size, the dd command can use /dev/zero as the input source, which provides an endless stream of zeros, and specify the output file name, the output block size (bs) and the count of blocks to copy. For example, dd if=/dev/zero of=file.txt bs=1k count=100 will create a file named file.txt that is 100kB in size. The file command can be used to determine the type of a file. The mkfile command is not a valid Linux command. The touch command can be used to create a new empty file or update the access and modification times of an existing file, but it does not specify the size of the file. References: [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.3: Perform basic file management, dd command, file command, touch command

When using regular expressions, the ^ character matches the beginning of a line. For example, ^Hello will match any line that starts with Hello. The ? character matches zero or one occurrence of the preceding character or group. For example, colou?r will match both color and colour. The * character matches zero or more occurrences of the preceding character or group. For example, ab*c will match ac, abc, abbc, abbbc, and so on. The + character matches one or more occurrences of the preceding character or group. For example, ab+c will match abc, abbc, abbbc, and so on, but not ac. The charactermatchestheendofaline.Forexample,World will match any line that ends with World. References: [LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.7: Use regular expressions with the standard Linux utilities, Regular Expressions

The program that updates the database that is used by the locate command is updatedb. The updatedb command creates or updates a database of filenames and directories that can be searched by the locate command. The updatedb command is usually run daily by cron to update the default database, which is stored in /var/lib/mlocate/mlocate.db. The updatedb command can also take some options, such as the filesystem type, the prune list, and the output file. For more information, see the updatedb man page1 or the Ubuntu man page2.

The command that will copy the current line into the vi buffer is yy. The yy command is a shorthand for yank yank, which means to yank (copy) the current line. The vi buffer is a temporary storage area where the copied text is stored until it is pasted somewhere else. The yy command can also be preceded by a number to indicate how many lines to copy. For example, the command 3yy will copy the current line and the next two lines into the buffer.

The other commands are incorrect for the following reasons:

A. c: This command is a shorthand for change, which means to delete the text specified by the following motion and enter insert mode. For example, the command cw will delete the current word and allow the user to type a new one.

B. cc: This command is a shorthand for change change, which means to delete the current line and enter insert mode. This command is similar to dd followed by i, but it is faster and more convenient.

C. 1c: This command is not valid, as it is missing a motion after the change command. The motion specifies what text to delete and replace. For example, the command 1cw will delete one word and enter insert mode.

E. 1y: This command is also not valid, as it is missing a motion after the yank command. The motion specifies what text to copy into the buffer. For example, the command 1yw will copy one word into the buffer.

??Thegrepcommandthatwillprintonlythelinesthatdonotendwitha/inthefilefooisgrep?v?/’ foo. This command uses the following options and pattern:

-v: Inverts the matching, meaning that it only outputs the lines that do not match the pattern. /:Matchesa/characterattheendofaline.The symbol represents the end of a line in regular expressions. foo: The name of the file to search.

The output of this command will show all the lines in the file foo that do not have a / as the last character. For example, if the file foo contains the following lines:

/home/user/ /var/log/messages /etc/passwd /usr/bin/

The output of the command will be:

/var/log/messages /etc/passwd

The other commands are incorrect for the following reasons:

grep ‘/$’ foo: This command will print only the lines that do end with a / in the file foo, which is the opposite of what is required.

grep ‘/#’ foo: This command will print only the lines that contain the string /# in the file foo, which is not related to the question.

grep -v ‘/#’ foo: This command will print only the lines that do not contain the string /# in the file foo, which is also not related to the question.

The swapoff command is used to disable swapping on a device or a file. It takes the path of the device or file as an argument, or -a to disable all swaps. Disabling swap can improve the performance of the system if there is enough physical memory, or it can be necessary if the swap size needs to be changed. However, disabling swap can also cause problems if the system runs out of memory and has no swap space to use. References:

How to Disable Swap in Linux - Linux Handbook

How to Permanently Disable Swap in Linux? - GeeksforGeeks

LPI Linux Essentials - 1.1 Operating System Basics

 The command apt-cache can be used to perform a full text search on all available packages on a Debian system. It searches the package names and the descriptions for an occurrence of the regular expression given as a keyword and prints out the package name and the short description1. The syntax is: apt-cache search keyword. For example, apt-cache search openssh will return a list of packages related to OpenSSH2. The other commands are not suitable for this task because:

apt is a high-level command-line tool that provides a user-friendly way to manage packages, but it does not have a search option3.

apt-get is a low-level command-line tool that handles the installation and removal of packages, but it does not have a search option4.

apt-search is not a valid command.

dpkg is a tool to install, build, remove and manage Debian packages, but it does not have a search option5. It can only list the installed packages with the option -l4. References:

How To Search For Available Packages From Command Line In Debian, Ubuntu Or Linux Mint [APT] - Linux Uprising Blog

apt(8) — apt — Debian buster — Debian Manpages

How to List Installed Packages on Debian | Linuxize

Debian / Ubuntu Linux search package names with apt-cache command

dpkg(1) — dpkg — Debian buster — Debian Manpages

The -a option to the tee command will cause the output to be appended to the end of the output file instead of overwriting the existing file contents. The tee command reads from standard input (STDIN) and writes to standard output (STDOUT) and one or more files simultaneously. For example, ls | tee file.txt will display the output of the ls command and also write it to file.txt. If file.txt already exists, it will be overwritten unless the -a option is used. References: LPI Exam 101 Detailed Objectives, Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.3: Perform basic file management, tee command

The program that runs a command in specific intervals and refreshes the display of the program’s output is watch. This command is used to run any designated command at regular intervals and displays the output of the command on the terminal window. It is useful when you have to execute a command repeatedly and watch the command output change over time. The syntax of the watch command is:

watch [options] command

The options can modify the behavior of the watch command, such as how to format the output, how to handle signals, or how to enable color. The command is the command that you want to run and monitor. The default interval between each execution of the command is 2 seconds, but you can change it with the -n or --interval option. For more help using the watch command and its options, run man watch or visit this link.

The command line that will create or, in case it already exists, overwrite a file called data with the output of ls is ls > data. The > character is a redirection operator that redirects the standard output (STDOUT) of a command to a file. If the file does not exist, it will be created. If the file already exists, it will be overwritten. The 3> character is not a valid redirection operator. The >& character is a redirection operator that redirects both standard output (STDOUT) and standard error (STDERR) of a command to a file. The >> character is a redirection operator that appends the standard output (STDOUT) of a command to a file, without overwriting the existing file contents. References: LPI Exam 101 Detailed Objectives, Topic 103: GNU and Unix Commands, Weight: 25, Objective 103.3: Perform basic file management, Redirection

The umask value that will result in the default access permissions of 600 (rw-------) for files and 700 (rwx------) for directories is 077. This is because the umask value is an octal number that represents the permissions that are not given to the files or directories. To calculate the umask value, we need to subtract the desired permissions from the maximum permissions, which are 666 for files and 777 for directories. For example, if we want the files to have the permissions 600 (rw-------), which means read and write for the owner and no permissions for the group and others, we need to subtract 600 from 666, which gives us 066. Similarly, if we want the directories to have the permissions 700 (rwx------), which means read, write, and execute for the owner and no permissions for the group and others, we need to subtract 700 from 777, which gives us 077. The umask value is the minimum of these two values, which is 077. The first digit of the umask value is for the special permissions, such as setuid, setgid, and sticky bit, and it is usually set to 0. Therefore, the final umask value is 077. For more information on how to use the umask command, you can refer to the following articles:

What Is umask in Linux, and How Do You Use It? - How-To Geek

Umask command in Linux with examples - GeeksforGeeks

What is UMASK and how to set UMASK in Linux/Unix?

How to Set and Update the Default Umask Value - phoenixNAP

The command that shows all shared libraries required by a binary executable or another shared library is ldd. This command queries the dynamic linker to find out which libraries are needed by the given file and displays them on the standard output. For example, to see the shared libraries required by the /bin/ls program, we can run:

ldd /bin/ls

The output will look something like this:

linux-vdso.so.1 (0x00007ffd8a7f6000)

libselinux.so.1 => /lib/x86_64-linux-gnu/libselinux.so.1 (0x00007f0c5a6c4000)

libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f0c5a4d3000)

libpcre2-8.so.0 => /usr/lib/x86_64-linux-gnu/libpcre2-8.so.0 (0x00007f0c5a445000)

libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f0c5a441000)

/lib64/ld-linux-x86-64.so.2 (0x00007f0c5a8a5000)

libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f0c5a41e000)

The output shows the name and the path of each shared library, as well as the address where it is loaded in memory. If the library is not found, the output will show not found instead of the path. The linux-vdso.so.1 library is a special case, as it is a virtual library that is not actually present on the filesystem, but is injected by the kernel into every process12.

The dpkg command is used to manage Debian packages on Linux systems. The -r option removes a package but leaves its configuration files in case the package is re-installed. The -P option purges a package and removes its configuration files as well. The -s option shows the status of a package and the -L option lists the files installed by a package. References:

LPI Linux Essentials, Chapter 6: Managing Software, Section 6.2: Debian Package Management

LPI Linux Administrator, Exam 101: System Architecture, Topic 102: Linux Installation and Package Management, Objective 102.5: Manage shared libraries

LPI Linux Engineer, Exam 201: Linux Kernel, Topic 201: System Architecture, Objective 201.1: Kernel Components and Compilation

The command that uninstalls a package but keeps its configuration files in case the package is re-installed is dpkg -r pkgname. The dpkg command is the low-level tool for installing, building, removing, and managing Debian packages. The -r or --remove option removes an installed package from the system, but it does not delete the configuration files and other data that belong to the package. This way, if the package is re-installed later, the previous settings are preserved. The dpkg command is part of the 101.1 Determine and configure hardware settings topic of the LPI Linux Essentials certification program12.

The other options are either invalid or do not perform the desired task. The dpkg -s pkgname command shows the status of an installed package, but it does not uninstall it. The dpkg -L pkgname command lists the files that belong to an installed package, but it does not uninstall it. The dpkg -P pkgname command purges an installed or removed package, which means it deletes the configuration files and other data that belong to the package. The dpkg -v pkgname command shows the version of an installed package, but it does not uninstall it.

The command that installs GRUB 2 into the master boot record on the third hard disk is grub-install /dev/sdc. The grub-install command is the high-level tool for installing GRUB 2 on a disk or a partition. It takes a device name as an argument and writes the GRUB 2 boot loader information to the specified location. If the device name is a disk, such as /dev/sdc, the boot loader information is written to the master boot record (MBR) of the disk, which is the first sector that contains the boot code and the partition table. If the device name is a partition, such as /dev/sdc1, the boot loader information is written to the boot sector of the partition, which is the first sector of the partition that contains the boot code and the file system information. The grub-install command is part of the 101.1 Determine and configure hardware settings topic of the LPI Linux Essentials certification program12.

The other commands are either invalid or do not perform the desired task. The grub2 install command does not exist, as grub2 is not a valid command name. The grub-mkrescue command is used to create a bootable GRUB 2 rescue image, not to install GRUB 2 on a disk or a partition3. The grub-mbrinstall command does not exist, as mbrinstall is not a valid subcommand for grub. The grub-setup command is a low-level tool for installing GRUB 2 on a disk or a partition, but it is not recommended for normal use, as it requires specifying the location of the GRUB 2 core image file4. References:

Linux Essentials - Linux Professional Institute Certification Programs1

Exam 101 Objectives - Linux Professional Institute2

GNU GRUB Manual 2.06: Making a GRUB bootable CD-ROM3

GNU GRUB Manual 2.06: Installing GRUB natively4

This command redirects the output of ls to standard error, which is file descriptor 2 by default. The syntax of the command is:

ls >& file_descriptor

The ls command is a utility that lists the files and directories in the current working directory or a specified directory. The >& symbol is a redirection operator that redirects the standard output of a command to another file descriptor, which can be a file, a device, or another stream. The file_descriptor is the number of the file descriptor to which the output is redirected.

Therefore, the command ls >&2 will run the ls command and redirect its output to file descriptor 2, which is standard error. This means that the output of ls will not be displayed on the screen, but sent to the standard error stream, which can be used for error handling or logging purposes.

The other commands are incorrect for the following reasons:

A, ls >-1: This command will not redirect the output of ls to standard error, but it will cause an error. The > symbol is a redirection operator that redirects the standard output of a command to a file or device, overwriting any existing content. The -1 argument is not a valid file name or device name, and it will cause the shell to report an error and exit.

B, ls <

D, ls >>2: This command will not redirect the output of ls to standard error, but it will append the output of ls to a file named 2. The >> symbol is a redirection operator that redirects the standard output of a command to a file or device, appending to any existing content. The 2 argument is the name of the file to which the output is appended. If the file does not exist, it will be created. The command will not display anything on the screen, but write the output of ls to the file 2.

E, ls |error: This command will not redirect the output of ls to standard error, but it will pipe the output of ls to another command named error. The | symbol is a pipe operator that redirects the standard output of one command to the standard input of another command. The error argument is the name of the command that receives the output of ls as its input. However, there is no such command named error in the Linux system, and the shell will report an error and exit.

The permissions -rwSr-xr-x mean that the file is readable and writable by the owner, readable and executable by the group, and readable and executable by others. The S in the owner’s permissions indicates that the file has the SetUID bit set, which means that when the file is executed as a command, it will run with the effective user ID of the file owner, rather than the user who executed it. This allows the command to perform privileged operations that the user normally cannot do. For example, the /bin/passwd command has the SetUID bit set, so that it can modify the /etc/shadow file, which is only writable by root. References: LPI Linux Administrator, File Permissions and Attributes

The correct answer is D, .bash_history. This file, located in a user’s home directory, contains the Bash history, which is a list of commands that the user has entered in the Bash shell. The syntax of the file is:

~/.bash_history

The ~ symbol represents the user’s home directory, which is usually /home/username. The / symbol is a directory separator that separates the components of a path. The . symbol at the beginning of the file name indicates that the file is hidden, which means that it is not normally displayed by the ls command or the file manager, unless the -a option or the show hidden files option is used. The bash_history is the name of the file that stores the Bash history.

The Bash history is maintained by the Bash shell while it is running, and it is written to the .bash_history file when the shell exits or when the history -a or -w options are used. The history command can be used to display, manipulate, or search the Bash history. The HISTFILE variable can be used to change the name or location of the .bash_history file. The HISTSIZE and HISTFILESIZE variables can be used to change the number of commands that are stored in the Bash history and the .bash_history file, respectively.

The other files are incorrect for the following reasons:

A, .bashrc_history: This file does not exist by default, and it is not used to store the Bash history. The .bashrc file is a configuration file that is executed by the Bash shell when it starts in interactive mode. It can contain commands, aliases, functions, variables, or other settings that affect the behavior of the shell. However, it is not used to store the history of the commands that the user has entered.

B, .bash_histfile: This file does not exist by default, and it is not used to store the Bash history. The .bash_histfile file is not a standard file name, and it is not recognized by the Bash shell. The Bash shell uses the .bash_history file to store the history of the commands that the user has entered, unless the HISTFILE variable is changed to a different file name.

C, .history: This file does not exist by default, and it is not used to store the Bash history. The .history file is not a standard file name, and it is not recognized by the Bash shell. The Bash shell uses the .bash_history file to store the history of the commands that the user has entered, unless the HISTFILE variable is changed to a different file name.

E, .history_bash: This file does not exist by default, and it is not used to store the Bash history. The .history_bash file is not a standard file name, and it is not recognized by the Bash shell. The Bash shell uses the .bash_history file to store the history of the commands that the user has entered, unless the HISTFILE variable is changed to a different file name.

The command chmod g+s sales sets the setgid bit on the directory sales, which means that any new file or subdirectory created within sales will inherit the group ownership of the directory. The command chmod 2775 sales does the same thing, but also sets the permissions of the directory to rwxrwxr-x, which means that the owner, group, and others can read, write, and execute files in the directory. Both commands ensure that new files created within the directory sales are owned by the group sales. The other commands are either invalid or do not affect the group ownership of new files. References:

Linux Essentials - Linux Professional Institute Certification Programs1

Exam 101 Objectives - Linux Professional Institute

The command grub-install is used to install GRUB on a device or a partition. The option --root-directory specifies the directory where GRUB images are put. The default is /boot/grub. The argument /dev/sda specifies the device where GRUB is installed, usually the Master Boot Record (MBR) of the disk. Therefore, the command grub-install --root-directory=/custom-grub /dev/sda will install GRUB on the MBR of /dev/sda and put the GRUB images under the directory /custom-grub/boot/grub. This means that the new configuration files, such as grub.cfg, will be found in the directory /custom-grub/boot/grub. References:

GNU GRUB Manual 2.06: Installing GRUB using grub-install

Installing GRUB using grub-install - GNU GRUB Manual 0.97

 The command foo 1> bar redirects the standard output (stdout) from the command foo to the file bar, overwriting the existing contents of the file. The number 1 before the redirection operator > indicates the file descriptor of the stdout stream, which is 1 by default. The redirection operator > means that the output of the command is written to the file, replacing any previous data in the file. The file name after the redirection operator is the destination of the output. For example, if the command foo prints “Hello world” to the stdout, and the file bar contains “Goodbye world”, the command foo 1> bar will write “Hello world” to the file bar, erasing “Goodbye world”. The other options are not correct because:

A. The stdout from the command foo is appended to the file bar: This is not what 1> does, because it overwrites the file, not appends to it. To append the output to the file, the operator >> should be used instead of >.

C. The command foo receives its stdin from the file bar: This is not what 1> does, because it redirects the output, not the input. To redirect the input from the file, the operator < should be used instead of >.

D. The command foo receives its stdin from the stdout of the command bar: This is not what 1> does, because it redirects the output to a file, not to another command. To redirect the output to another command, the operator | (pipe) should be used instead of >.

E. The stderr from the command foo is saved to the file bar: This is not what 1> does, because it redirects the stdout, not the stderr. To redirect the stderr, the file descriptor 2 should be used instead of 1.

 When removing a package on a system using dpkg package management, the --purge option ensures that configuration files are removed as well. The --purge option is equivalent to the --remove option followed by the --purge-config-files option, which removes any configuration files that are marked as obsolete. The --remove option only removes the package files, but leaves the configuration files intact. The --clean option removes any .deb files from the local cache, but does not affect the installed packages. The --delete option is not a valid option for dpkg. References:

1, 102.4 Lesson 1

3, 101-500 Exam - Free Questions and Answers - ITExams.com

man dpkg

The /etc/yum.repos.d/ directory contains configuration files for additional yum repositories. Each file in this directory should end with .repo and contain information about one or more repositories. The yum command will read all the files in this directory and use them as sources for software packages. The format of the .repo files is similar to the /etc/yum.conf file, which contains the main configuration options for yum. Each .repo file can have one or more sections, each starting with [repository] where repository is a unique identifier for the repository. The section can have various options, such as name, baseurl, enabled, gpgcheck, etc. For example, a .repo file for the EPEL repository could look like this:

[epel] name=Extra Packages for Enterprise Linux 7 - $basearch baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch enabled=1 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

 The apt-get command upgrade will install the newest versions of all currently installed packages without removing any packages or installing new packages that are not already installed. It will only upgrade packages that can be upgraded without changing the dependencies1. The syntax is: apt-get upgrade. For example, apt-get upgrade nginx will update the nginx package to the latest version available in the repositories, if there is one2. The other options are not correct because:

auto-update is not a valid apt-get command.

dist-upgrade will also install new packages or remove existing packages if that is required to resolve a package conflict1. It is more aggressive than upgrade and may change the system in unexpected ways3.

install will install new packages or upgrade existing packages to the specified version1. It may also install or remove dependencies as needed4.

update will only resynchronize the package index files from the sources, but it will not install or upgrade any packages1. References:

apt-get(8) — apt — Debian buster — Debian Manpages

How to Update Nginx on Ubuntu 18.04 | Linuxize

What is “dist-upgrade” and why does it upgrade more than “upgrade”? - Ask Ubuntu

How to Install Specific Version of Package using apt-get - TecAdmin

 The RPM command that will output the name of the package which supplied the file /etc/exports is rpm -qf /etc/exports. This command will query the RPM database and find the package that owns or provides the file /etc/exports1. The output will show the package name, version, release, and architecture. For example:

The other options are incorrect for the following reasons:

rpm -F /etc/exports. This command will try to freshen or upgrade the package that contains the file /etc/exports, if it is already installed2. This command will not output the package name, but rather install the latest version of the package from a specified source. For example:

rpm -Kl /etc/exports. This command is not valid, as RPM does not have a -Kl option. The -K option is used to verify the signatures of the RPM package files, not the installed files3. The -l option is used to list the files in a package, not to query the package name. For example:

rpm -qp /etc/exports. This command will try to query the package information of the file /etc/exports, as if it was an RPM package file. This command will not output the package name, but rather an error message, as /etc/exports is not a valid RPM package file. For example:

rpm -qi /etc/exports. This command will try to query the information of the package /etc/exports, as if it was an installed package name. This command will not output the package name, but rather an error message, as /etc/exports is not a valid package name. For example:

The top-level system directory that is used for files and data that change regularly while the system is running and are to be kept between reboots is /var. The /var directory contains variable data that changes in size as the system runs. For instance, log files, mail directories, databases, and printing spools are stored in /var. These files and data are not temporary and need to be preserved across system reboots. The /var directory is one of the few directories that are recommended to be on a separate partition, according to the Filesystem Hierarchy Standard (FHS)1. This is because the /var directory can grow unpredictably and fill up the / partition, which can cause system instability or failure. By having /var on a separate partition, we can limit the amount of disk space that can be used by variable data and prevent users from affecting the / partition. The /var directory is also a common target for malicious attacks, so having it on a separate partition can improve the security and isolation of the system. References:

Filesystem Hierarchy Standard

 The function key that is used to start Safe Mode in Windows NT is none of the above, because Windows NT does not support Safe Mode. Safe Mode is a diagnostic mode of Windows that starts the system with minimal drivers and services, allowing the user to troubleshoot problems and restore the system to a normal state1. Safe Mode was introduced in Windows 95 and later versions, but not in Windows NT 4.0 and earlier2.

The other options are incorrect for the following reasons:

F10. This function key is used to access the Recovery Console in Windows XP, which is a command-line interface that allows the user to perform various administrative tasks, such as repairing the boot sector, restoring the registry, or copying files3. The Recovery Console is not the same as Safe Mode, and it is not available in Windows NT.

F8. This function key is used to access the Advanced Boot Options menu in Windows Vista and later versions, which allows the user to choose from various boot modes, including Safe Mode, Last Known Good Configuration, Debugging Mode, and others4. In Windows NT, pressing F8 during startup only displays a simple menu with three options: Normal, VGA mode, and Boot Logging5. None of these options are equivalent to Safe Mode.

F6. This function key is used to load additional drivers during the installation of Windows, such as SCSI or RAID drivers, from a floppy disk or a USB flash drive6. This function key has nothing to do with Safe Mode, and it is not relevant after the installation is completed.

The yum command is a tool for managing software packages on Red Hat Enterprise Linux and other RPM-based systems. The yum update option will update the entire system by checking the versions of the installed packages and installing the latest available versions from the repositories. The yum upgrade option will do the same, but it will also remove any obsolete packages that are no longer needed by the system. Both options will prompt the user to confirm before proceeding with the update or upgrade process. References:

Yum Command Cheat Sheet for Red Hat Enterprise Linux

"yum update" Explained for Beginners!

How to Install Updates on CentOS 7

Which option to the yum command will update the entire system?

The dd command is used to copy data from one device or file to another, with optional parameters to specify the block size (bs), the number of blocks to copy (count), and other options. The bootloader is typically located in the first 440 bytes of the disk, which is the Master Boot Record (MBR) area. The MBR also contains the partition table, which starts at byte 446 and occupies 64 bytes. Therefore, to overwrite the bootloader without affecting the partition table or any data following it, the command should copy 440 bytes from /dev/zero (a special device that provides null bytes) to /dev/sda (the disk device) and stop after one block. This is achieved by the command: dd if=/dev/zero of=/dev/sda bs=440 count=1 References:

LPI Exam 101 Detailed Objectives, section 1.101.3

dd man page

Master Boot Record

 The apt-cache command is used to query the APT cache for information about packages. The depends option shows a listing of each dependency a package has and all the possible other packages that can fulfill that dependency. For example, apt-cache depends ubuntu-restricted-extras will show the dependencies of the ubuntu-restricted-extras package. The other options are not valid for the apt-cache command. References:

How to Check Dependencies of a Package in Ubuntu/Debian-based Linux Distributions

Check DEB package dependencies on Ubuntu / Debian

The timeout option in a GRUB Legacy configuration file is used to define the amount of time (in seconds) that the GRUB menu will be shown to the user before booting the default entry. The timeout option is usually located in the /boot/grub/menu.lst file. For example, timeout 10 will display the GRUB menu for 10 seconds. To disable the timeout and wait for user input indefinitely, the value of timeout can be set to -1. To boot immediately without displaying the menu, the value of timeout can be set to 0. The other options are not valid for the GRUB Legacy configuration file. References:

GRUB Legacy - ArchWiki

How do I set the grub timeout and the grub default boot entry?

How to Remove the Timeout From GRUB Menu

The command dpkg-reconfigure is a Debian package management tool that asks the configuration questions for a specific already installed package just as if the package were being installed for the first time. It can be used to reconfigure a package that was previously installed with default settings, or to change the settings of a package that requires user input during installation. It can also be used to fix a broken configuration file or to restore the original configuration file of a package. References:

Debian Reference: Chapter 2. Debian package management

LPI Linux Essentials: 1.3 Package Management

 The Logical Volume Manager (LVM) is a tool that allows the creation and management of logical volumes on Linux systems. Logical volumes are partitions that can span multiple physical disks and can be resized or deleted without affecting the rest of the system. Some of the benefits of using LVM are:

To dynamically change the size of logical volumes. LVM allows the user to increase or decrease the size of a logical volume without having to repartition the disk or reboot the system. This can be useful for allocating more space to a volume that is running out of space, or freeing up space from a volume that is not needed anymore.

To create snapshots. LVM allows the user to create a snapshot of a logical volume, which is a copy of the volume at a certain point in time. Snapshots can be used for backup purposes, as they can be restored to the original volume if needed. Snapshots can also be used for testing purposes, as they can be mounted as read-only or read-write volumes without affecting the original volume.

To dynamically create or delete logical volumes. LVM allows the user to create or delete logical volumes on the fly, without having to repartition the disk or reboot the system. This can be useful for creating temporary volumes for specific purposes, or deleting volumes that are no longer needed.

LVM cannot be used for the following purposes:

To create RAID 9 arrays. RAID 9 is not a valid RAID level, and LVM does not support RAID functionality. RAID is a technique that uses multiple disks to provide redundancy, performance, or both. RAID can be implemented at the hardware level, by using a RAID controller, or at the software level, by using tools such as mdadm or dmraid. LVM can work on top of RAID devices, but it cannot create them.

To encrypt logical volumes. LVM does not provide encryption functionality. Encryption is a technique that protects data from unauthorized access by using a secret key to transform the data into an unreadable form. Encryption can be implemented at the disk level, by using tools such as dm-crypt or LUKS, or at the file system level, by using tools such as eCryptfs or EncFS. LVM can work on top of encrypted devices, but it cannot encrypt them.