Why switch to Zsh and Oh-My-Zsh ?

Modern terminal users expect faster workflows, better history search, auto-suggestions, and a customizable prompt. Zsh, paired with Oh My Zsh, provides these improvements immediately.

What Zsh improves over Bash ?

Installation Workflow (High-Level Overview)

flowchart TD
    A[Start Terminal] --> B[Install Zsh]
    B --> C[Set Zsh as Default Shell]
    C --> D[Install Oh My Zsh]
    D --> E[Install Plugins]
    E --> F[Configure .zshrc]
    F --> G[Apply Theme]
    G --> H[Restart Shell]
    H --> I[Enhanced Terminal Experience]

Step 1: Update Your Linux System

Before installing Zsh, refresh package lists and upgrade current packages.

This ensures compatibility and avoids dependency issues.

sudo apt update -y && sudo apt upgrade -y

Step 2: Install Zsh

sudo apt install zsh -y

# Verify installation
which zsh
# Expected output: /bin/zsh

Step 3: Make Zsh Your Default Shell

Important: Log out and log back in for changes to apply. If your terminal still opens in Bash, check the troubleshooting section below.

chsh -s /bin/zsh

Step 4: Install Oh-My-Zsh Framework

The official installer downloads and configures Oh My Zsh automatically.

Below script creates:

• ~/.oh-my-zsh/ directory.
• Updated ~/.zshrc configuration.
• Core initialization scripts.

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

Step 5: Initial post-installation setup

5.1 Import old Bash Hhistory (Recommended)

Zsh can start suggesting your previously used commands immediately.

Note:

• If .zsh_history already contains Zsh metadata, you can ignore this step as it will overwrite zsh history.
• For safety, back it up: cp ~/.zsh_history ~/.zsh_history_backup

cp ~/.bash_history ~/.zsh_history
fc -R ~/.zsh_history

5.2 Improve autosuggestion visibility

Some terminal themes make suggestions hard to see.

Customize the highlight color:

# Place this BEFORE plugin loading in ~/.zshrc
ZSH_AUTOSUGGEST_HIGHLIGHT_STYLE="fg=#ff00ff"

Step 6: Recommended Plugins

The Oh-My-Zsh plugin ecosystem greatly boosts productivity.

Here is some of the useful plugins to start with

6.1 Install auto-suggestions plugin

git clone https://github.com/zsh-users/zsh-autosuggestions \
  ${ZSH_CUSTOM:-~/.oh-my-zsh/custom}/plugins/zsh-autosuggestions

Enable it in .zshrc:

# Open zsh config file
nano ~/.zshrc

# Conf
plugins=(git zsh-autosuggestions)

# Reload the changes
source ~/.zshrc

How Auto-Suggestions work

sequenceDiagram
    participant U as User
    participant Z as Zsh
    participant A as Autosuggest
    participant H as History

    U->>Z: Types text
    Z->>A: Request suggestion
    A->>H: Search history
    H-->>A: Return best match
    A-->>U: Show faded suggestion
    U->>Z: Accept (Right Arrow)

Step 7: Choose and apply a Zsh theme

Themes define your prompt layout, icons, colors, and performance.

Factors to consider

• Minimal vs modern vs powerline
• Font compatibility (some require Nerd Fonts / Powerline fonts)
• Prompt speed (complex themes load slower)
• Information density (git, directory, time, exit code, etc.)

Popular Built-in themes

Applying a theme

Edit .zshrc:

ZSH_THEME="agnoster"
source ~/.zshrc

Try different themes, until you find one that suits your workflow.

Step 8: Build Your Own Custom Theme (Optional)

Create and place your theme file at:

~/.oh-my-zsh/themes/mycustomtheme.zsh-theme

Use below minimal custom theme to start

# ~/.oh-my-zsh/themes/mycustomtheme.zsh-theme

# Prompt: username@host (green) + last 2 dirs (blue) + prompt char + git status
PROMPT="%{$fg_bold[green]%}%n@%m%{$reset_color%} \
%{$fg_bold[blue]%}%2~%{$reset_color%} \
%{$fg_bold[white]%}%#%{$reset_color%} "

# Display git branch
PROMPT+='$(git_prompt_info)'

# Git prompt formatting
ZSH_THEME_GIT_PROMPT_PREFIX="%{$fg_bold[blue]%}git:(%{$fg[red]%}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%} "
ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[blue]%}) %{$fg[yellow]%}✗%{$reset_color%}"
ZSH_THEME_GIT_PROMPT_CLEAN="%{$fg[blue]%})%{$reset_color%}"

Enable the theme

# Update theme
ZSH_THEME="mycustomtheme"

# Reload the config
source ~/.zshrc

Oh-My-Zsh directory structure

Knowing the folder layout helps you manage plugins, themes, and customizations properly.

graph LR
    A[~/.oh-my-zsh] --> B[themes/]
    A --> C[plugins/]
    A --> D[lib/]
    A --> E[custom/]
    E --> F[custom themes]
    E --> G[custom plugins]
    A --> H[oh-my-zsh.sh]

Troubleshooting

Terminal still opens in Bash ?

Add this to ~/.bashrc, it forces interactive Bash sessions to switch into Zsh.

if [ -t 1 ] && [ "$SHELL" != "/bin/zsh" ]; then
    exec zsh
fi

Uninstalling Oh-My-Zsh safely

Step 1: Restore Bash history

Zsh adds metadata timestamps.

Clean them before merging back into Bash history.

# Backup bash history
cp ~/.bash_history ~/.bash_history_backup

# clean and update bash history
sed 's/^: [0-9]*:[0-9]*;//' ~/.zsh_history >> ~/.bash_history

# sort the history
sort -u ~/.bash_history -o ~/.bash_history

Step 2: Remove auto-switch script

Edit ~/.bashrc and remove or comment this block.

if [ -t 1 ] && [ "$SHELL" != "/bin/zsh" ]; then
    exec zsh
fi

Step 3: Switch back to Bash & remove Zsh

# Set default shell to Bash
chsh -s /bin/bash

# load history
history -r ~/.bash_history

# remove Zsh
sudo apt remove --purge zsh
sudo apt autoremove

Summary

This article provides a complete workflow of: setup → enhance → customize → maintain.

Your Linux terminal is now:

• Faster
• More customizable
• More productive
• Much easier to use

You learned how to:

• Install Zsh
• Install Oh My Zsh
• Enable plugins
• Apply and create themes
• Sync Bash history
• Fix shell startup issues
• Uninstall cleanly