Free Practice Questions for LPI 101-500 Exam

The vi command is a text editor that operates in two modes: command mode and insert mode. Command mode is used to enter commands to manipulate the text, such as saving, quitting, copying, pasting, etc. Insert mode is used to enter text into the file. When the vi command is invoked without any additional parameters, it starts in command mode and opens a new empty file. To enter text, the user has to press i to switch to insert mode. To return to command mode, the user has to press Esc. To save and quit, the user has to enter :wq in command mode. The other options are either incorrect or not applicable. The vi command does not load the last file used or the content of the vi buffer by default. It also does not require the user to explicitly create or load a file. It does not exit with an error message unless there is a problem with the terminal or the system. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.7 Use and edit text files

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

The cut command is used to extract selected fields from each line of a file. The -d option specifies the delimiter that separates the fields, and the -f option specifies the fields to print. The /etc/passwd file contains information about the users on the system, and each field is separated by a colon (:). Therefore, cut -d : -f 1,4 /etc/passwd will print the first and fourth fields of each line, which are the username and the primary group ID respectively. The other commands are either invalid or do not perform the desired task. The fmt command is used to reformat paragraphs of text, but it does not have a -f option. The split command is used to split a file into smaller files, but it does not have a -c option. The paste command is used to merge lines of files, but it does not have a -f option. References:

LPIC-1 Exam 101 Objectives, Topic 103: GNU and Unix Commands, 103.3 Perform basic file management

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

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 command that will reduce all consecutive spaces down to a single space is tr -s ’ ’ < a.txt > b.txt. This command uses the following options and syntax:

-s: Squeezes repeated characters listed in the first set with single occurrence.

’ ': Specifies a space character as the first set.

< a.txt: Redirects the input from a file named a.txt.

b.txt: Redirects the output to a file named b.txt.

The output of this command will be a new file called b.txt that contains the same text as a.txt, except that any sequence of multiple spaces will be replaced by a single space. For example, if the file a.txt contains the following text:

This is a text file with multiple spaces.

The file b.txt will contain the following text:

This is a text file with multiple spaces.

The other commands are incorrect for the following reasons:

A. tr ‘\s’ ’ ’ < a.txt > b.txt: This command will replace every whitespace character (\s) with a space character, which will not reduce the number of spaces, but rather convert tabs and newlines into spaces.

B. tr -c ’ ’ < a.txt > b.txt: This command will complement the first set, meaning that it will apply the operation to all characters that are not spaces. This will not affect the spaces at all, but rather squeeze all other characters.

C. tr -d ’ ’ < a.txt > b.txt: This command will delete all spaces from the input, which will not reduce them to a single space, but rather remove them completely.

D. tr -r ’ ’ ‘\n’ < a.txt > b.txt: This command will replace all spaces with newlines, which will not reduce the spaces, but rather create a new line for each word.

The shell redirection that will write standard output and standard error output to a file named filename is >filename 2>&1. This command uses the following syntax:

filename: Redirects standard output (file descriptor 1) to a file named filename. If the file does not exist, it will be created. If the file exists, it will be overwritten.

2>&1: Redirects standard error (file descriptor 2) to the same destination as standard output. The & symbol indicates that the following number is a file descriptor, not a filename.

The order of the redirections is important, as they are processed from left to right. If the order was reversed, as in 2>&1 >filename, the command would not work as expected, because it would first redirect standard error to the current standard output (which is the terminal by default), and then redirect standard output to the file, leaving standard error unchanged.

The other commands are incorrect for the following reasons:

A. 2>&1 >filename: This command will redirect standard error to the current standard output, and then redirect standard output to the file, leaving standard error unchanged.

C. 1>&2>filename: This command will redirect standard output to the current standard error, and then redirect standard error to the file, leaving standard output unchanged.

D. >>filename: This command will only redirect standard output to the file in append mode, without affecting standard error.

E. 1&2>filename: This command is not valid, as it is missing the > symbol before the first file descriptor, and it will produce an error message.

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 /tmp directory should be on a separate partition if possible because it is world writable. This means that any user can create, modify, or delete files and directories in /tmp. This can pose a risk of filling up the / partition, which can cause system instability or failure. By having /tmp on a separate partition, we can limit the amount of disk space that can be used by temporary files and prevent users from affecting the / partition. The /tmp 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. The /tmp directory is one of the few directories that are world writable by default, according to the Filesystem Hierarchy Standard (FHS)1. The other directories that are usually world writable are /var/tmp and /var/lock, which are also used for temporary or lock files. However, these directories are not as frequently used or as large as /tmp, so they are less likely to fill up the / partition. The /tmp directory also has the sticky bit set, which means that only the owner of a file or directory can delete or rename it2. This prevents users from deleting or modifying other users’ files in /tmp. However, this does not prevent users from creating new files or directories in /tmp, which can still consume disk space and resources. Therefore, it is advisable to have /tmp on a separate partition if possible. References:

Filesystem Hierarchy Standard

Sticky bit - Wikipedia

After modifying GNU GRUB’s configuration file, which is usually located at /etc/default/grub, the command that must be run for the changes to take effect is grub-install12. The grub-install command is used to install GRUB on a device or partition, and to update the boot sector and the core image of GRUB3. The command takes the following basic syntax:

$ grub-install [options] install_device

The install_device argument specifies the device or partition where GRUB should be installed, such as /dev/sda or /dev/sda1. The options can be used to control various aspects of the installation, such as the target platform, the boot directory, the force mode, the verbosity level, etc3.

The grub-install command also invokes the grub-mkconfig command, which generates the GRUB configuration file (usually located at /boot/grub/grub.cfg) based on the settings in /etc/default/grub and the scripts in /etc/grub.d4. The grub-mkconfig command can also be run separately to update the GRUB configuration file without reinstalling GRUB on the device or partition4.

The other options in the question are not correct because:

A. kill -HUP $(pidof grub): This command would send the hangup signal (HUP) to the process ID (PID) of grub, which is a command-line interface for GRUB. This would not update the GRUB configuration file or install GRUB on the device or partition.

C. grub: This command would run the command-line interface for GRUB, which allows the user to interact with GRUB and execute various commands. This would not update the GRUB configuration file or install GRUB on the device or partition, unless the user explicitly runs the appropriate commands within the interface.

D. No action is required: This option is false, because modifying the /etc/default/grub file alone does not affect the GRUB configuration file or the GRUB installation. The user needs to run either grub-install or grub-mkconfig to apply the changes.

 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