LPI 101-500 Exam With Confidence Using Practice Dumps

The .bash_history file, located in the user home directory, is used to store the Bash history. The Bash history is a list of commands that the user has entered in the Bash shell. The .bash_history file is created when the user first starts a Bash session, and is updated when the user exits the session or runs the history command with the -a or -w option. The user can view the contents of the .bash_history file with the cat command, or use the history command to see the numbered list of commands. The user can also edit, delete, or clear the .bash_history file with various commands and options. The location and name of the history file can be changed by setting the HISTFILE environment variable to a different value. References:

[LPI Exam 101 Detailed Objectives], Topic 103: GNU and Unix Commands, Objective 103.1: Work on the command line, Weight: 4, Key Knowledge Areas: Use of history and HISTFILE.

Where is bash’s history stored?, Topic: Bash maintains the list of commands internally in memory while it’s running.

QUESTIONNO: 26

Which Bash environment variable defines in which file the user history is stored when exiting a Bash process? (Specify ONLY the variable name.)

Answer: HISTFILE

The HISTFILE environment variable defines in which file the user history is stored when exiting a Bash process. The user history is a list of commands that the user has entered in the Bash shell. By default, the HISTFILE variable is set to ~/.bash_history, which means that the history is stored in a hidden file called .bash_history in the user’s home directory. The user can change the value of the HISTFILE variable to store the history in a different file or location. For example, the following command will set the HISTFILE variable to ~/my_history:

export HISTFILE=~/my_history

This will cause the history to be stored in a file called my_history in the user’s home directory. The user can also unset the HISTFILE variable to disable the history saving feature. For example, the following command will unset the HISTFILE variable:

unset HISTFILE

This will prevent the history from being written to any file when the Bash process exits. The user can view the value of the HISTFILE variable by using the echo command. For example, the following command will display the value of the HISTFILE variable:

echo $HISTFILE

The output will be something like:

/home/user/.bash_history

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.