Shell Selection & Configuration

Learn about different shells available in Xermius Local Terminal, how to choose the right one, and configure it for your workflow.

What is a Shell?

Simple Explanation: A shell is the program that interprets your commands and talks to the operating system. It's the "language" you use in the terminal.

Analogy:

You → Shell → Operating System → Hardware

Like a translator between you and the computer!

Popular Shells:

Bash (most common)
Zsh (modern, powerful)
Fish (user-friendly)
PowerShell (Windows-native)

Available Shells

1. Bash (Bourne Again Shell)

Overview:

✅ Most widely used
✅ Universal compatibility
✅ Huge ecosystem
✅ Default on many systems

Best for:

General purpose use
Shell scripting
Maximum compatibility
Learning Unix/Linux

Version check:

bash --version
# GNU bash, version 5.2.15

Key Features:

Command history
Tab completion
Job control
Aliases and functions
Script automation

Example session:

# Bash prompt
user@computer:~$ 

# Use wildcards
ls *.txt

# Command substitution
echo "Today is $(date)"

# Pipes and redirection
cat file.txt | grep "search" > results.txt

2. Zsh (Z Shell)

Overview:

✅ Enhanced features
✅ Better autocomplete
✅ Plugin ecosystem (oh-my-zsh)
✅ Default on macOS (since Catalina)

Best for:

Power users
Advanced customization
Plugin lovers
Modern development

Version check:

zsh --version
# zsh 5.9

Key Features:

Advanced tab completion
Spelling correction
Theme support
Plugin system (oh-my-zsh)
Better globbing
Shared history

Example session:

# Zsh prompt (with oh-my-zsh)
➜ ~ 

# Advanced completion
git che<TAB>
# Shows: checkout, cherry, cherry-pick

# Spelling correction
$ mkdri newdir
zsh: correct 'mkdri' to 'mkdir' [nyae]?

# Better globbing
ls **/*.js  # Recursive search

# Plugin features (with oh-my-zsh)
gst  # Alias for git status
gaa  # Alias for git add --all

oh-my-zsh:

# Install oh-my-zsh (in local terminal)
sh -c "$(curl -fsSL https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

# Edit config
nano ~/.zshrc

# Change theme
ZSH_THEME="agnoster"

# Enable plugins
plugins=(git node npm docker kubectl)

# Reload
source ~/.zshrc

3. Fish (Friendly Interactive Shell)

Overview:

✅ Very user-friendly
✅ Syntax highlighting
✅ Autosuggestions
✅ Web-based configuration

Best for:

Beginners
Interactive use
Modern UX
Visual feedback

Version check:

fish --version
# fish, version 3.6.1

Key Features:

Syntax highlighting (colors)
Autosuggestions from history
Tab completions from man pages
Web-based configuration
No configuration needed

Example session:

# Fish prompt
user@computer ~>

# Syntax highlighting (colors as you type)
$ ls -la
  ↑ Command turns green (valid)
  
$ lss -la
  ↑ Command turns red (invalid)

# Autosuggestions (gray text from history)
$ git commit█
$ git commit -m "Update feature"
  ↑ Suggestion appears as you type
  Press → to accept

# Web configuration
$ fish_config
# Opens browser with GUI configuration

Fish configuration:

# Edit config
nano ~/.config/fish/config.fish

# Add alias
alias ll='ls -la'

# Add function
function mkcd
    mkdir -p $argv
    cd $argv
end

# Save and reload
source ~/.config/fish/config.fish

4. PowerShell

Overview:

✅ Windows-native
✅ Object-based (not text)
✅ .NET integration
✅ Cross-platform (Core)

Best for:

Windows users
.NET development
Windows automation
System administration

Version check:

$PSVersionTable.PSVersion
# Major  Minor  Build  Revision
# 7      3      4      0

Key Features:

Object pipelines
Cmdlets (verb-noun commands)
Tab completion
Script automation
.NET framework access

Example session:

# PowerShell prompt
PS C:\Users\user>

# Object-based commands
Get-Process | Where-Object CPU -gt 100
Get-ChildItem -Recurse -Filter *.txt

# Cmdlet pattern
Get-Help Get-Process
Set-Location C:\Projects
New-Item -Type Directory -Name NewFolder

# Aliases for familiar commands
ls  # Alias for Get-ChildItem
pwd # Alias for Get-Location
cd  # Alias for Set-Location

Comparison Table

Feature	Bash	Zsh	Fish	PowerShell
Ease of Use	⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐
Compatibility	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐ (Windows)
Customization	⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐⭐
Autocomplete	⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐⭐
Speed	⭐⭐⭐⭐	⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐
Scripting	⭐⭐⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐⭐
Plugins	⭐⭐⭐	⭐⭐⭐⭐⭐	⭐⭐⭐	⭐⭐⭐
Learning Curve	Easy	Medium	Very Easy	Medium
Default On	Linux	macOS	-	Windows

Selecting Your Shell

In Xermius Settings

Change default shell:

1. Settings → Terminal → Default Shell
2. Choose from dropdown:
   - System Default (recommended)
   - Bash
   - Zsh
   - Fish
   - PowerShell
   - Custom Path...
3. Save

New local terminals will use selected shell

Per-Terminal Selection

Override for single terminal:

1. New Local Terminal → More Options
2. Select Shell:
   - [System Default]
   - [Bash]
   - [Zsh]
   - [Fish]
   - [PowerShell]
3. Open

This terminal uses selected shell only

System Default Shell

Check system default:

macOS/Linux:

echo $SHELL
# /bin/bash or /bin/zsh

Change system default (macOS/Linux):

# Change to Zsh
chsh -s /bin/zsh

# Change to Bash
chsh -s /bin/bash

# Change to Fish
chsh -s /usr/local/bin/fish

# Takes effect after logout/login

Windows:

# PowerShell is default
# Can change in Windows Terminal settings

Shell Configuration

Bash Configuration

Config files:

~/.bashrc       # Interactive shells
~/.bash_profile # Login shells (macOS)
~/.bash_aliases # Aliases

Basic configuration:

# Edit ~/.bashrc
nano ~/.bashrc

# Add customizations:

# Prompt
export PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '

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

# PATH additions
export PATH="$HOME/.local/bin:$PATH"

# History settings
export HISTSIZE=10000
export HISTFILESIZE=20000

# Save and reload
source ~/.bashrc

Useful additions:

# Colorful ls
export CLICOLOR=1
export LSCOLORS=GxFxCxDxBxegedabagaced

# Better history
shopt -s histappend
PROMPT_COMMAND='history -a'

# Case-insensitive completion
bind 'set completion-ignore-case on'

Zsh Configuration

Config file:

~/.zshrc  # Main config

Basic configuration:

# Edit ~/.zshrc
nano ~/.zshrc

# Prompt
PROMPT='%F{green}%n@%m%f:%F{blue}%~%f$ '

# Aliases (same as Bash)
alias ll='ls -la'
alias ..='cd ..'
alias gs='git status'

# Auto-correction
setopt CORRECT
setopt CORRECT_ALL

# History
HISTSIZE=10000
SAVEHIST=10000
HISTFILE=~/.zsh_history

# Save and reload
source ~/.zshrc

With oh-my-zsh:

# Already installed during oh-my-zsh setup
nano ~/.zshrc

# Choose theme
ZSH_THEME="robbyrussell"  # Default
# Or: agnoster, powerlevel10k, spaceship, etc.

# Enable plugins
plugins=(
  git
  docker
  kubectl
  npm
  node
  python
  vscode
  zsh-autosuggestions
  zsh-syntax-highlighting
)

# Custom settings
ZSH_AUTOSUGGEST_HIGHLIGHT_STYLE='fg=8'

source ~/.zshrc

Fish Configuration

Config file:

~/.config/fish/config.fish

Basic configuration:

# Edit config
nano ~/.config/fish/config.fish

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

# Functions
function mkcd
    mkdir -p $argv
    cd $argv
end

# Environment variables
set -x PATH $HOME/.local/bin $PATH

# Save and reload
source ~/.config/fish/config.fish

Web configuration:

# Open GUI configuration
fish_config

# Configure:
- Theme
- Prompt
- Colors
- Variables
- Functions
- Abbreviations

# Changes saved automatically

PowerShell Configuration

Config file:

$PROFILE  # Shows path
# Usually: C:\Users\user\Documents\PowerShell\Microsoft.PowerShell_profile.ps1

Basic configuration:

# Edit profile
notepad $PROFILE

# Add customizations:

# Aliases
Set-Alias ll Get-ChildItem
Set-Alias g git

# Functions
function mkcd($path) {
    New-Item -Type Directory -Path $path
    Set-Location $path
}

# Prompt customization
function prompt {
    "$env:USERNAME@$env:COMPUTERNAME:$(Get-Location)> "
}

# Save and reload
. $PROFILE

Shell-Specific Tips

Bash Tips

1. Keyboard shortcuts:

Ctrl+A  # Start of line
Ctrl+E  # End of line
Ctrl+R  # Reverse search
Ctrl+W  # Delete word
Ctrl+K  # Delete to end

2. Parameter expansion:

# Remove extension
filename="document.pdf"
echo ${filename%.pdf}  # document

# Default value
echo ${VAR:-default}  # Use default if VAR empty

# String replacement
text="hello world"
echo ${text/world/bash}  # hello bash

3. Here documents:

cat << EOF > file.txt
Line 1
Line 2
Line 3
EOF

Zsh Tips

1. Advanced globbing:

# Recursive search
ls **/*.js

# Numeric ranges
ls file<1-10>.txt

# Excluding patterns
ls ^*.txt  # All except .txt files

2. Suffix aliases:

# Auto-open files by extension
alias -s js=code
alias -s txt=nano
alias -s pdf=open

# Now just type filename:
document.pdf  # Opens with default PDF viewer

3. Global aliases:

alias -g G='| grep'
alias -g L='| less'
alias -g H='| head'
alias -g T='| tail'

# Use anywhere:
ps aux G node  # ps aux | grep node
cat file L     # cat file | less

Fish Tips

1. Abbreviations:

# Like aliases but expand
abbr -a gco git checkout
abbr -a gcm git commit -m
abbr -a gp git push

# Type 'gco' and space → expands to 'git checkout'

2. Universal variables:

# Set across all sessions
set -U fish_color_command blue
set -U PATH $PATH /new/path

# Persist automatically

3. Event handlers:

# Run on directory change
function on_pwd_change --on-variable PWD
    # Auto-activate venv if exists
    if test -e venv/bin/activate.fish
        source venv/bin/activate.fish
    end
end

PowerShell Tips

1. Pipeline objects:

# Select properties
Get-Process | Select-Object Name, CPU

# Where clause
Get-ChildItem | Where-Object Length -gt 1MB

# Sorting
Get-Process | Sort-Object CPU -Descending

2. Modules:

# Import module
Import-Module posh-git

# List modules
Get-Module -ListAvailable

# Install from gallery
Install-Module -Name PSReadLine

3. Profile functions:

# Quick navigation
function dev { Set-Location C:\Dev }
function proj { Set-Location C:\Projects }

# Git shortcuts
function gs { git status }
function ga { git add $args }

Troubleshooting

Shell Not Found

Issue: Selected shell doesn't exist

Solution:

# Check if shell is installed
which bash
which zsh
which fish

# Install if missing (macOS)
brew install zsh
brew install fish

# Install if missing (Linux)
sudo apt install zsh
sudo apt install fish

# Then restart Xermius

Shell Configuration Errors

Issue: Shell won't start or shows errors

Causes:

Syntax error in config file
Missing command in config
Broken plugin

Solutions:

1. Test configuration:

# Bash
bash --norc  # Start without config
bash -n ~/.bashrc  # Check syntax

# Zsh
zsh -f  # Start without config
zsh -n ~/.zshrc  # Check syntax

# Fish
fish --no-config
fish -n ~/.config/fish/config.fish

2. Find error:

# Add debug output
set -x  # Enable debug mode

# Source config
source ~/.bashrc

# Disable debug
set +x

3. Reset configuration:

# Backup current
cp ~/.bashrc ~/.bashrc.backup

# Use default
cp /etc/skel/.bashrc ~/.bashrc

# Or delete and recreate
mv ~/.bashrc ~/.bashrc.old
# Restart terminal (creates default)

Plugins Not Working

Issue: Shell plugins don't load

Zsh (oh-my-zsh):

# Reinstall oh-my-zsh
sh -c "$(curl -fsSL https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

# Update plugins
cd ~/.oh-my-zsh
git pull

# Check plugin syntax
nano ~/.zshrc
# Ensure: plugins=(git docker ...)

Fish:

# Reinstall Fisher (if used)
curl -sL https://raw.githubusercontent.com/jorgebucaran/fisher/main/functions/fisher.fish | source && fisher install jorgebucaran/fisher

# Reinstall plugins
fisher update

Recommendations

For Beginners

Start with: Bash or Fish

Why:

Bash: Universal, lots of tutorials
Fish: Very user-friendly, helpful hints

Avoid (initially):

Zsh with heavy customization (overwhelming)
PowerShell (unless Windows-focused)

For Power Users

Choose: Zsh with oh-my-zsh

Why:

Maximum customization
Huge plugin ecosystem
Best autocomplete
Active community

Configure:

Install oh-my-zsh
Choose modern theme (powerlevel10k)
Enable useful plugins
Custom aliases/functions

For Windows Users

Primary: PowerShell

Why:

Native Windows integration
Best for Windows administration
Object-based (powerful)

Alternative: Git Bash

Unix-like commands on Windows
Good for cross-platform work

For Scripters

Recommended: Bash

Why:

Most portable
Widely documented
Best compatibility
Standard for DevOps scripts

Alternative: Zsh

Compatible with Bash scripts (mostly)
Additional features for interactive use

Next Steps

📘 Local Terminal Overview - Learn the basics
💻 Using Local Terminal - Practical workflows
🆚 Local vs SSH Terminal - Understand differences
⌨️ Keyboard Shortcuts - Work faster

What is a Shell?​

Available Shells​

1. Bash (Bourne Again Shell)​

2. Zsh (Z Shell)​

3. Fish (Friendly Interactive Shell)​

4. PowerShell​

Comparison Table​

Selecting Your Shell​

In Xermius Settings​

Per-Terminal Selection​

System Default Shell​

Shell Configuration​

Bash Configuration​

Zsh Configuration​

Fish Configuration​

PowerShell Configuration​

Shell-Specific Tips​

Bash Tips​

Zsh Tips​

Fish Tips​

PowerShell Tips​

Troubleshooting​

Shell Not Found​

Shell Configuration Errors​

Plugins Not Working​

Recommendations​

For Beginners​

For Power Users​

For Windows Users​

For Scripters​

Next Steps​

What is a Shell?

Available Shells

1. Bash (Bourne Again Shell)

2. Zsh (Z Shell)

3. Fish (Friendly Interactive Shell)

4. PowerShell

Comparison Table

Selecting Your Shell

In Xermius Settings

Per-Terminal Selection

System Default Shell

Shell Configuration

Bash Configuration

Zsh Configuration

Fish Configuration

PowerShell Configuration

Shell-Specific Tips

Bash Tips

Zsh Tips

Fish Tips

PowerShell Tips

Troubleshooting

Shell Not Found

Shell Configuration Errors

Plugins Not Working

Recommendations

For Beginners

For Power Users

For Windows Users

For Scripters

Next Steps