1.9 - CompTIA A+ Core 2

/etc/passwd

Linux config file that lists all registered users and their information, including username, password, UID, GID, and home directory.

/etc/shadow

Linux config file that contains hashed versions of all users' passwords, viewable only by root or elevated users.

/etc/hosts

Linux config file that stores IP addresses and their corresponding FQDNs, used to override DNS resolution.

/etc/resolv.conf

Linux config file that stores IP addresses of DNS nameservers for resolving domain names.

/etc/fstab

Stands for File Systems Table; lists all system disks and partitions on a Linux machine.

systemd

A system and service manager that starts, stops, and manages background services/software (daemons) in Linux.

Kernel

The core of the operating system that manages system processes and interacts with devices.

Kernel space

Protected area of memory used for kernel operations.

Bootloader

A computer component that starts the correct operating system from a bootable drive.

Root account

The administrative user account in a Unix or Linux operating system that has full access to all system commands and files.

ls

Command that lists the content in a directory, similar to the dir command in Windows.

pwd

Command that displays the current directory working path.

mv

Command used to move or rename files in a directory.

cp

Command used to duplicate files or directories.

rm

Command used to remove files or directories.

rm -r

Variant of the rm command used to remove directories.

chmod

Command that changes the mode (permissions) of a file system object.

Read, write, and execute - octal

7

Read, and write - octal

6

Read and execute (r-x) - octal

5

Read only (r--) - octal

4

Write and execute (-wx) - octal

3

Write only (-w-) - octal

2

Execute only (--x) - octal

1

No permissions (---) - octal

0

chown

Command that changes the owner of a file or directory to a specified user and/or group.

grep

Command used to search through many Linux files for a specified pattern.

find

Command used to locate a file by its name or extension.

fsck

Command used to check and repair a Linux filesystem.

mount

Command used to access and assign a storage device to a directory.

su

Command allowing a user to switch to the root account or another user account.

sudo

Command that allows execution of a command as the super/root user.

apt

Command used for installing, updating, and removing application packages.

dnf

Dandified YUM - a package manager for Linux that allows installation, removal, and updating of packages.

ip

Command used to manage network interfaces and view IP addresses.

ping

Command used to check the reachability of a device on a network.

curl

Command used to retrieve data via a URL.

dig

Command that provides lookup information from DNS servers.

traceroute

Command that tracks the path that packets take from one computer to another.

man

Command that displays a reference manual for a particular command.

cat

Command used to output the content of a file to the terminal.

top

Command that displays system resource usage information such as CPU and RAM.

ps

Command that shows all current processes on a Linux machine.

du

Command that shows disk usage for files or directories.

df

Command that displays available storage space on Linux file systems.

nano

A command-line text editor with syntax highlighting and other user-friendly features.