The watch command can be used with any command, so that it is replayed constantly, the default time is 2 seconds, but the -n option allows you to set the update time. The free command displays the RAM and System Swap usage, the -m option shows the value in Mega.

Zypper is the rpm package manager used in OpenSuse systems. The options are similar to yum, but not the same. In general there is a long option, for example “zypper install ksh“ or short, “zypper in ksh“.

In the rpm command, used for direct installation of .rpm packages, the -U option can be used to install or update a package that already exists. The rpm -i option will only perform a fresh install, but will not update a package that is already installed. The –force option forces the installation of a package, for example the command “rpm -ivh –force new-software.rpm“ would force reinstallation of the new-software.rpm package, overwriting the previous files, in other words, it doesn’t upgrade to a new version.

When there’s more than one string in the variable, they must be grouped by quotation marks. Can’t have any spaces before or after the = signal.

The command env show only the exported variables, while the comand set shows even local variables.

? C. type
The type command is used to display information about how the shell will interpret a given command. When you execute type cd, the output cd is a shell builtin precisely indicates that cd is not an external executable but rather a command built directly into the shell (like Bash or Zsh). This is the exact output specified in the question.

? A. file
The file command is used to determine the file type of files. When given cd as an argument (and if cd refers to a file, which it typically doesn‘t as it‘s a builtin), it would try to identify its content type (e.g., “ASCII text“, “ELF 64-bit LSB executable“). It would not state “cd is a shell builtin.“

? B. which
The which command displays the full path of (shell) commands. If cd were an executable file found in the system‘s PATH, which cd would output its full path (e.g., /usr/bin/cd, though cd is usually a builtin). However, for a shell builtin, which typically returns nothing or an error, as it doesn‘t exist as a separate executable file. It would certainly not state “cd is a shell builtin.“

? D. whatis
The whatis command displays a very brief description of a command (from the man pages). For cd, it might output something like “cd (1) – change the working directory“. It would not provide information about cd being a “shell builtin.“

The command “uniq -d“ shows only the duplicate lines as long as the file is sorted. “Uniq -u“ has the opposite effect and shows only the unique lines, sort -d sorts only blank lines and alphanumeric characters, and -r sorts in reverse order.

When using “cd“ and “cd ~“ the user returns to his default directory. Because the value of the $ HOME variable is the user‘s default directory, “cd $ HOME“ has the same effect. The “cd -“ returns to the previous directory, and $ USER contains only the username.

The -p option in the mkdir causes the entire tree to be created. Without this option an error would occur because of the lack of the course and class1 directories.

In this case, the find command should be used with the syntax “find“ “. The character * means that any character (or group of) can be between “report“ and “csv“. In this find command, que quotes must be used because of the use of *. The “iname“ also could be used, because is the same of “name“, but being case insensitve.

The < symbol indicates that “data“ will be the input of the “generate-report“ command, while the “2>“ symbol indicates that the error output (stderr) will be sent to the errors.log file.

0 is the standard input descriptor (stdin), 1 is the standard output descriptor (stdout) and 2 is the output error (stderr).

There are two possible syntaxes to execute a command inside another, using the command between quotes (not single quotes), for example ′command′, or use the command inside $(command). Note that the use of single quotation marks at the beginning and end of a sentence will cause the sub commands to not be executed. Also note the syntax of date options that should be date +%X.

The function of the tee command is to receive an input, usually the output of another command with the use of |, display this input on the screen and at the same time write it to a file.

The pkill and killall commands use the name of the process as an argument, pkill allows several other variables such as the user name of the process owner, for example. The kill uses the PID as argument, pgrep only shows the PID of a process.

The command “yum install –downloadonly “ will only download an rpm package from the configured repositories, but will not install it.

Without any parameter, kill sends the SIGTERM signal, code 15, this signal kills the process in a soft way, giving the process time to complete its tasks.

The jobs command shows all processes (or set of them) started in the background, using & in the current session.

The “nice” of a process can be configured with values ranging from -20 to 19, where -20 increases the priority to the maximum, and 19 decreases to the maximum.

The renice syntax is: renice NICE_VALUE PID, so -15 is the “nice” value -15. Note that the syntax of the “nice” command is a bit different: nice -NICE_VALUE command, so if “nice -15” command is used, the “nice” value associated with the command would be 15.

In grep, the -c option counts the occurrences of the string, in how many lines the string appeared. The -l shows the files that have a certain string. fgrep is a grep that does not accept any type of regular expression. Egrep is a grep that accepts extended regular expressions but the -n option would only include a number in the rows of the result.

The ^ character always indicates something at the beginning of the line. The $ character indicates the end of a line. The grep -v would exclude every occurrence of the word Carlos. Egrep ^carlos has the first lowercase letter, since the function is case-sensitive, the string Carlos would not be found.

Attention, because the statement says that the current line and the next 20 lines, that is, 21 lines, must be erased, in this way the 21dd or d21d commands can be used.

The df command is used to check the use of a partition, usually shows the disk space, but with the -i option it displays the use of inodes. This information can also be checked with “tune2fs -l“ command.

The “users“ option does what is described in the statement, the “user“ option allows any user to mount a partition, but only the user who mounted it can unmount it. The nouser causes ordinary users to not mount the partition, remount reassembles a partition already mounted, without having to unmount it.

Mount is the command used to manually mount a partition to a directory, with the syntax: mount

In systemd, a mount point is a type of Unit, so just use the list-units option of systemctl specifying the type “mount“.

The chgrp command is specific for group definition with the syntax: chgrp . The chown command can be used to set the user owner and the group, accepting the following syntaxes: chown : ou chown . , where the can be ommited.

Permissions are set by subtracting the umask value from value 666 for files and 777 for directories. Thus, the value 0002, which may also appear as 002, will be 666 – 002 = 664 (rw-rw-r–).

The value 6 corresponds to the permissions r and w, read and write. In this way, 660 enables read and write for users and groups, but no permissions for other users of the system.

The commands :wq, 😡 and ZZ will save the document and leave VI. :q! leaves without save and XX doesn’t exist.

Correct Answer: C. systemctl status httpd Explanation: The systemctl status command provides detailed information about a specific service, including whether it‘s active, its main PID, and recent log entries. Option A is incorrect. systemctl show provides property information about a unit, but not the detailed status information that systemctl status provides. Option B is incorrect. systemctl list is not a valid systemctl command. Option D is incorrect. systemctl info is not a valid command in systemd.

Correct Answer: B. wall < alert.txt Explanation: To send a message saved in a file to all users using the wall command, Carlos can redirect the content of the file as input to wall. This is accomplished with the < redirection operator. Option A is incorrect. The -f option does not exist for the wall command. Option C is incorrect. The -m option does not exist for the wall command. Option D is incorrect. The --message option does not exist for the wall command.

Correct Answer: B. dpkg-reconfigure timezone-data Explanation: The dpkg-reconfigure command allows users to reconfigure packages that have been previously installed and configured. If Samantha wants to reconfigure the timezone-data package, she should use the dpkg-reconfigure timezone-data command. Option A is incorrect. There is no -reconfig option for dpkg. The correct command is dpkg-reconfigure. Option C is incorrect. dpkg –configure configures unpacked packages, but it doesn‘t provide the interactive reconfiguration interface like dpkg-reconfigure. Option D is incorrect. There is no –reset option for dpkg.

Correct Answer: C. dpkg -i software-package.deb Explanation: The dpkg -i command is used to install a .deb package. In this scenario, Robert would use dpkg -i software-package.deb to install the provided package. Option A is incorrect. dpkg -c is used to list the contents of a .deb package and does not install it. Option B is incorrect. While dpkg –unpack unpacks the files from a package, it doesn‘t configure them. To fully install a package, the -i option is more appropriate as it unpacks and configures the package. Option D is incorrect. dpkg –search is used to search for a filename from installed packages and has nothing to do with installing a package.

Correct Answer: D. /usr/lib/systemd/system-preset/ Explanation: The /usr/lib/systemd/system-preset/ directory contains vendor-provided presets for systemd units. Presets are a way to manage the enablement state of unit files, determining which services should be enabled or disabled by default. Option A is incorrect. There is no default directory named /usr/lib/systemd/defaults/ for systemd. Option B is incorrect. The /usr/lib/systemd/presets/ directory does not exist as a default for storing vendor-provided system unit presets. Option C is incorrect. The /usr/lib/systemd/system-presets/ directory is not the standard directory for system unit presets.

Correct Answer: B. chgrp -R developers project_files Explanation: The -R option in the chgrp command is used to operate on files and directories recursively. Hence, to change the group ownership of a directory and all its contents, the -R option should be used. Option A is incorrect. Without the ′-R′ option, only the directory‘s group ownership will be changed, and not its contents. Option C is incorrect. Though it contains the correct elements, the order of the arguments is not conventional, and while it might work on some systems, it‘s not the standard order. Option D is incorrect. The order of the arguments is incorrect. The group name should come before the target.

Correct Answer: A. ls *.txt | cpio -o > documents.cpio Explanation: The cpio -o option is used to create an archive. The ls *.txt command lists all .txt files in the current directory. By piping (|) the output of ls to cpio -o, it tells cpio to archive the listed files. Option B is incorrect. The use of input redirection (′<′) with ′cpio -o′ is incorrect in this context. We want to feed the list of files to ′cpio′ using a pipe, not input redirection. Option C is incorrect. The ′-i′ option is used for extracting archives, not creating them. Option D is incorrect. The ′-i′ option, as stated earlier, is used for extracting, and input redirection is not used correctly here.

Correct Answer: C. apt-get upgrade Explanation: The apt-get upgrade command is used to upgrade all currently installed packages on a Debian system. It will not remove any packages or install new ones. Option A is incorrect. There‘s no –upgrade-all option for the apt-get install command. Option B is incorrect. apt-get update fetches the list of available packages and their versions but doesn‘t upgrade any packages. Option D is incorrect. apt-get dist-upgrade upgrades packages, considering dependencies, and can also install new packages or remove existing ones to satisfy dependencies.

The root directory (/) is the first partition that has to be mounted. After that, the system will have access to the main configuration files in /etc, like, for instance, the /etc/fstab, and, with that, will obtain information about the other partitions to be mounted.

The commands “man” and “info” will show, in most of the cases, a whole manual about each command. “whatis” will bring a brief definition about the tool function.

The command dmesg has as an output a register of the logs in the system boot, the same information can be found in the file /var/log/dmesg, however, not all distributions currently include this file. In the journalctl, the -k options shows all the kernel messages from the current boot, the -b option can also be used but contains all messages, not only kernel related.

“wall” will send the message that follows the command directly to the terminal where all the users are connected.

The /usr/share contains many system files, including the documentation pages in /usr/share/doc and the manuals in /usr/share/man.

System V, or SysV, is the init that was originally used in Linux environments, inherited from Unix. Currently most distributions use the systemd and some use Upstart. Anacron is a process scheduling tool.

Correct Answer: A. ln database_original database_link Explanation: The ln command without any options is used to create hard links. The first argument is the source (existing file) and the second argument is the name of the new hard link. Option B is incorrect. The ′-s′ option creates a symbolic link, not a hard link. Option C is incorrect. While ′link′ might sound relevant, it‘s not the standard command for creating links in this context. Option D is incorrect. The ′-h′ option is not a valid option for the ′ln′ command when creating hard links.

It’s important to remember that a partition with ID 82 (0x82) will be assigned to the swap area, while partitions with ID 83 (0x83), Linux Native, will be used to Linux files. The swap area of a system can be composed of several partitions.

The GRUB settings must be made in /etc/default/grub, after using update-grub or grub-mkconfig is when the file /boot/grub/grub.cfg will be updated. The file menu.lst is used for GRUB Legacy, not for GRUB2.

If there’s no specified parameter, split command will split a file in other files with 1000 lines each. The -l option can be used to set the desired number of lines and the -b option to set in bytes.

The ldd command followed by the application‘s name will show the dynamic libraries used by the application. The ldconfig is used to update the directory bases in which the shared libraries can be found. In practice, the ldconfig updates the file /etc/ld.so.cache based on the settings of /etc/ld/so.conf. The updatedb updates the base used with the command locate.

The file /etc/apt/sources.list contains a list of URLs and parameters used by the APT commands to check and download the new packages.

The command dpkg-reconfigure can be used to reconfigure a package already installed, like, for example, the keyboard sets with “dkpg-reconfigue keyboard-configuation”. The “apt-get update” only updates the the repository information, “dselect“ is a menu interface for dpkg and apt reconfigure does not exist.

xfs_repair repairs corrupt or damaged XFS filesystems The e2fsck is only for ext2, ext3 and ext4. xfs_fsr is the filesystem reorganizer for XFS. The syntax for fsck is wrong, but even using fsck.xfs or fsck -t xfs, the command will indicate the use of xfs_repair.

The MBR area is located in the first sector of the bootable disk, contains the information for loading the bootloader (GRUB) and the system partition table. MBR loads and runs GRUB. The Power On Self Test (POST) is a test performed by the BIOS on the hardware components connected to the motherboard. The kernel is responsible for starting the init .

lspci is a utility for displaying information about PCI buses in the system and devices connected to them.

The lsusb command is used to list the devices connected to the USB buses, the -s option is used to view the details based on the Bus and Device values, the -d option is used with the values that follow the “ID“, always in with the -v option to display the details.

The -r option of the shutdown command can be used to reboot the system, as well as the reboot command. Telinit 6 invokes runlevel 6 which is related to rebooting the system. Runlevel 0 is related to the shutdown procedure.

Some directories can not be mounted on partitions other than the / partition. The / partition is the first to be mounted, and after that, configuration files and tools will be used to finalize the system boot, including mounting other partitions, if these files are on different partitions, they will not be accessible. The directories that should be on the same partition are /etc, /sbin, /bin, /lib, /media, /mnt, /proc, /sys, /dev.

The grub-install command will install the GRUB files on the indicated device, by default in the /boot directory. The grub-mkconfig and update-grub commands have the function of updating the GRUB files in /boot, based on what has been configured by the administrator.

“dpkg -s“, “apt-cache show“ and “apt show“ will return various information from a package installed on the system. “Dpkg -L“ lists the files associated with a given package. The “status“ option in apt-get does not exist.