Linux Installation, File System, and Shell Basics

What Is Linux and Why Does It Matter in IT Support?

Linux is an open-source, Unix-like operating system kernel first released by Linus Torvalds in 1991. Distributions ("distros") bundle the kernel with software packages, a package manager, and desktop environments to create complete operating systems. Ubuntu is one of the most widely used desktop and server distributions. Its Long-Term Support (LTS) releases receive security updates for five years, making them a practical choice in business and lab environments. CompTIA A+ Core 2 includes Linux/macOS objectives, and both Cisco CCST and CCNA assume comfort with command-line interfaces that share conventions with Linux shells.

Virtualization and Safe Lab Practice

A virtual machine (VM) runs inside host software—in this course, Oracle VirtualBox—so you can install and experiment with an OS without affecting your workstation. Before you begin:

• Electrical safety: Workstations should already be powered and grounded. Do not open the physical chassis during this lab; no internal hardware work is involved.
• Data safety: Never use a VM disk file stored on a shared network drive where it could consume space used by others without permission.
• Resource limits: Allocate only as much RAM and disk as the instructor specifies. Over-allocating RAM can freeze the host machine, affecting all students.

For Ubuntu desktop, a minimum of 2 GB RAM and 20 GB of virtual disk is a common starting point, though 4 GB RAM produces a smoother experience if the host allows it.

Disk Partitioning Basics

During installation, Ubuntu's installer lets you partition the virtual disk. Three partitions matter most in a standard Linux setup:

| Partition | Mount Point | Purpose |

|-----------|------------|----------|

| Root | `/` | Core OS files and installed software |

| Home | `/home` | User data and personal settings |

| Swap | (no mount point) | Overflow space when RAM is full; similar in concept to Windows paging file |

For a guided lab install you may accept a single root partition, which is fine. Understanding the separate-home pattern is important because enterprise systems separate `/home` so a reinstall does not erase user data.

The Linux File-System Hierarchy

Linux organizes everything under a single root, written as `/`. Key directories defined by the Filesystem Hierarchy Standard (FHS) include:

• `/bin` — essential user command binaries (e.g., `ls`, `cp`)
• `/etc` — system-wide configuration files
• `/home` — home directories for regular users (e.g., `/home/student`)
• `/var` — variable data such as logs (`/var/log`)
• `/tmp` — temporary files cleared on reboot
• `/usr` — secondary hierarchy for user programs and documentation
• `/dev` — device files representing hardware

There are no drive letters (no C: or D:). External drives and USB sticks are mounted into subdirectories of this single tree.

Essential Shell Commands

The default shell on Ubuntu is Bash (Bourne Again SHell). The prompt ends with `$` for a regular user and `#` for root. Core commands you will use in this lab:

Navigation and listing

• `pwd` — print working directory (shows your current location)
• `cd /path/to/dir` — change directory; `cd ..` moves up one level; `cd ~` returns to your home directory
• `ls -la` — list all files including hidden ones (`-a`) in long format (`-l`), showing permissions, owner, size, and date

File and directory management

• `mkdir dirname` — make a new directory
• `rmdir dirname` — remove an empty directory
• `rm -r dirname` — remove a directory and its contents recursively (use with care—there is no recycle bin)
• `cp source destination` — copy a file
• `mv source destination` — move or rename a file

Viewing file contents

• `cat filename` — print the entire file to the screen
• `less filename` — page through a file; press `q` to quit

System information

• `uname -a` — displays kernel version and architecture
• `df -h` — disk free space in human-readable units
• `free -h` — RAM and swap usage

Getting Help: man Pages and --help

Every well-written Linux command includes built-in documentation. Two access methods:

• `man ls` — opens the manual page for `ls`; use arrow keys to scroll, `q` to quit. Man pages follow a consistent format: NAME, SYNOPSIS, DESCRIPTION, OPTIONS, EXAMPLES.
• `ls --help` — prints a shorter usage summary directly to the terminal.

For the A+ exam and real-world support, the ability to locate and read documentation independently is as important as memorizing syntax.

Lab Log and Accuracy

Record every command you run and the output you receive. If a command fails, copy the error message into the log and note what you tried next. This mirrors professional troubleshooting documentation and will be reviewed by your instructor as part of the completion check.

Safety Checklist Before You Start

1. Confirm VirtualBox is installed and your user account has permission to create VMs.

2. Verify the Ubuntu LTS ISO checksum if instructed—this confirms the file was not corrupted in transit.

3. Do not install software on the host OS without instructor approval.

4. Save your VM snapshot after a clean install so you can restore it if something goes wrong later in the course.