Part 4: Environment Mastery - Customizing Your Shell

By Ayush Chauhan

9th Nov 2025
3 min read
Tags:
linux,
workshop,
tutorial,
command-line,
bash

Welcome to Part 4! Now we’ll make the terminal truly yours by customizing your shell environment.

Understanding Your Shell

Your shell is the program that interprets your commands. Most Linux systems use Bash (Bourne Again SHell), but others like Zsh and Fish are popular too.

Check your shell:

echo $SHELL
# Output: /bin/bash (or /bin/zsh, etc.)

Exercise 4.1:

echo $SHELL
bash --version

Environment Variables

Environment variables are like global settings for your shell. They store information that programs can access.

Viewing Environment Variables

env                     # List all environment variables
echo $HOME              # Your home directory
echo $USER              # Your username
echo $PATH              # Where the shell looks for commands
echo $PWD               # Current directory
echo $SHELL             # Your shell program

Exercise 4.2:

env | grep USER
echo $HOME
echo $PATH

Understanding `$PATH`

$PATH is critical. It’s a colon-separated list of directories where the shell looks for commands.

echo $PATH
# Output: /usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games

When you type ls, the shell searches these directories in order:

/usr/local/bin/ls
/usr/bin/ls ← Found! (stops searching)
/bin/ls

Exercise 4.3:

echo $PATH
which ls                # Shows which 'ls' is being used
which python3

Setting Environment Variables

Temporary (current session only):

export MY_VAR="Hello"
echo $MY_VAR

export PATH="$PATH:$HOME/bin"    # Add to PATH

Permanent (edit .bashrc or .bash_profile):

# We'll do this in the next section!

Exercise 4.4:

export WORKSHOP="Linux CLI"
echo $WORKSHOP
echo "I'm learning $WORKSHOP"

# Try in a new terminal - it's gone! (temporary)

Common Environment Variables

$HOME           # Your home directory
$USER           # Your username
$HOSTNAME       # Computer name
$PWD            # Current directory
$OLDPWD         # Previous directory
$PATH           # Command search path
$SHELL          # Your shell
$EDITOR         # Default text editor
$LANG           # Language settings
$PS1            # Prompt string

The `.bashrc` File

The .bashrc file is a script that runs every time you open a new terminal. This is where you customize your shell!

Location: ~/.bashrc (hidden file in your home directory)

Exercise 4.5:

cd ~
ls -la | grep bashrc
cat ~/.bashrc | head -20

Editing `.bashrc`

⚠️ Important: Always backup before editing!

cp ~/.bashrc ~/.bashrc.backup
nano ~/.bashrc          # or: vim ~/.bashrc, code ~/.bashrc

Apply changes:

source ~/.bashrc        # Reload the file
# OR
. ~/.bashrc             # Same thing (. is shorthand for source)
# OR
exec bash               # Restart the shell

Aliases - Your Personal Shortcuts

Aliases are shortcuts for long commands. They make you faster and save typing.

Creating Aliases

Temporary (current session):

alias ll='ls -la'
alias gs='git status'
alias ..='cd ..'

Permanent (add to .bashrc):

nano ~/.bashrc
# Add at the end:
# alias ll='ls -la'
# alias gs='git status'
# alias ..='cd ..'
source ~/.bashrc

Exercise 4.6:

# Create temporary aliases
alias ll='ls -lah'
alias c='clear'
alias h='history'

# Try them
ll
c
h

Useful Aliases to Add

Open your .bashrc and add these:

# Navigation
alias ..='cd ..'
alias ...='cd ../..'
alias ~='cd ~'

# Listing
alias ll='ls -lah'
alias la='ls -A'
alias l='ls -CF'

# Safety
alias rm='rm -i'        # Confirm before delete
alias cp='cp -i'        # Confirm before overwrite
alias mv='mv -i'        # Confirm before overwrite

# Git shortcuts
alias gs='git status'
alias ga='git add'
alias gc='git commit'
alias gp='git push'
alias gl='git log --oneline'

# System
alias df='df -h'
alias du='du -h'
alias free='free -h'
alias ports='netstat -tulanp'

# Quick edit
alias bashrc='nano ~/.bashrc'
alias reload='source ~/.bashrc'

# Miscellaneous
alias now='date +"%T"'
alias nowdate='date +"%d-%m-%Y"'
alias weather='curl wttr.in'

Exercise 4.7:

# Add these to your .bashrc
nano ~/.bashrc

# Add at the end:
alias ll='ls -lah'
alias ..='cd ..'
alias gs='git status'
alias reload='source ~/.bashrc'

# Save (Ctrl+O, Enter, Ctrl+X in nano)
source ~/.bashrc

# Test
ll
..
reload

Viewing and Removing Aliases

alias                   # List all aliases
alias ll                # Show specific alias
unalias ll              # Remove alias (temporary)

Customizing Your Prompt (`$PS1`)

The prompt is the text before your cursor. By default: user@hostname:~$

See your current prompt:

echo $PS1
# Output: \u@\h:\w\$

Prompt escape codes:

\u - Username
\h - Hostname
\w - Full working directory
\W - Current directory name only
\$ - $ for normal user, # for root
\d - Date
\t - Time (24-hour)
\n - Newline

Exercise 4.8 - Simple custom prompt:

# Try these (temporary)
PS1="\u@\h:\w\$ "               # Default
PS1="[\t] \u:\w\$ "             # Add time
PS1="\w > "                     # Minimalist
PS1="\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ "  # Colors!

Make it permanent - add to .bashrc:

# Colorful prompt (green user@host, blue directory)
PS1="\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ "

The berzifetch Project

Now let’s do something cool! We’ll install and configure berzifetch - a system information tool written by a friend.

What is berzifetch?

berzifetch displays your system information in a beautiful format. Think of it like neofetch but customizable!

Repository: github.com/Spirizeon/berzifetch

Installing berzifetch

Exercise 4.9:

# Clone the repository
cd
git clone https://github.com/Spirizeon/berzifetch.git
cd berzifetch

# Read the README
cat README.md

# Try it
./main

Adding berzifetch to Your PATH

Copy to a directory already in PATH:

sudo cp main /usr/local/bin/berzifetch
# Now you can run: berzifetch (from anywhere)

# Reload
source ~/.bashrc

# Verify
which berzifetch
berzifetch

Creating a berzifetch Alias

Let’s make it run every time you open a terminal!

Exercise 4.11:

nano ~/.bashrc

# Add at the end:
alias fetch='~/berzifetch/main'

# OR make it auto-run on terminal startup:
~/berzifetch/main

# Save and reload
source ~/.bashrc

Now every new terminal shows your system info!

Functions in `.bashrc`

Functions are like aliases on steroids - they can accept arguments!

Exercise 4.12 - Add these functions to .bashrc:

# Create a directory and enter it
mkcd() {
    mkdir -p "$1" && cd "$1"
}

# Extract any archive
extract() {
    if [ -f "$1" ]; then
        case "$1" in
            *.tar.gz)   tar xzf "$1"    ;;
            *.zip)      unzip "$1"      ;;
            *.rar)      unrar x "$1"    ;;
            *.tar)      tar xf "$1"     ;;
            *)          echo "Unknown archive format" ;;
        esac
    else
        echo "File not found"
    fi
}

# Quick backup
backup() {
    cp "$1" "$1.backup-$(date +%Y%m%d-%H%M%S)"
}

# Find process by name
psgrep() {
    ps aux | grep -v grep | grep -i -e VSZ -e "$1"
}

Usage:

source ~/.bashrc

mkcd test_folder        # Creates and enters directory
backup important.txt    # Creates timestamped backup
psgrep firefox          # Find Firefox processes

Hands-On Challenge

Ready to practice? Complete the hands-on challenge in the workshop repository:

Part 4 Challenge on GitHub

Challenge: Customize your shell with useful aliases and functions to boost your productivity.

The challenge includes:

Specific aliases to add to your config
A useful function to create
Verification that everything works
Bonus customizations to explore

Clone the repository and give it a try:

git clone https://github.com/bakayu/linux-tutorial.git
cd linux-tutorial/04-environment-customization
cat README.md

Advanced: Shell Configuration Files

Different files load at different times:

~/.bash_profile     # Login shells (SSH, first terminal)
~/.bashrc           # Interactive shells (new terminal tabs)
~/.bash_logout      # When you logout
~/.bash_aliases     # Separate file for aliases (sourced by .bashrc)

Best practice: Put everything in .bashrc, then have .bash_profile source it:

# ~/.bash_profile
if [ -f ~/.bashrc ]; then
    source ~/.bashrc
fi

Quick Reference Card

# Environment Variables
export VAR="value"      # Set variable
echo $VAR               # Print variable
env                     # List all variables
echo $PATH              # Command search path

# Configuration
nano ~/.bashrc          # Edit config
source ~/.bashrc        # Reload config
cp ~/.bashrc ~/backup   # Backup

# Aliases
alias ll='ls -la'       # Create alias
alias                   # List aliases
unalias ll              # Remove alias

# Functions
function_name() {       # Define function
    commands
}

# PATH Management
export PATH="$PATH:/new/path"   # Add to PATH
which command                    # Find command location