This guide explains how to install Windows Subsystem for Linux (WSL), configure the Alacritty terminal with Tmux, set up the Berkeley Mono font, and install CLI tools for Claude, Gemini, and Codex.

Part 1: System & Terminal Setup

1. Install WSL (Windows Subsystem for Linux)

  1. Open PowerShell as Administrator.
  2. Run the command: 
    wsl --install
  3. Restart the computer when prompted.
  4. After rebooting, a terminal window will open to set up your Ubuntu username and password.

2. Install Alacritty (Windows)

Alacritty is a terminal emulator that runs on Windows, connecting to WSL.

  1. Install: Use a package manager like Winget (pre-installed on Windows 11/10) or download from GitHub. 
    winget install Alacritty.Alacritty

  2. Configure for WSL: Find or create the config file at %APPDATA%\Roaming\alacritty\alacritty.toml (or .yml for older versions).

    Add the following to launch WSL by default:

    [terminal]
shell = { program = "wsl.exe", args = ["~"] }

3. Install Tmux (Inside WSL)

  1. Open your newly installed Alacritty (it should launch into Ubuntu/WSL).
  2. Update repositories and install Tmux: 
    sudo apt update && sudo apt install tmux -y
  3. create ~/.tmux.conf file: 
    touch ~/.tmux.conf

    and add the following content:

     # ==========================================
 # 1. General Settings
 # ==========================================
 set -g default-terminal "tmux-256color"
 set -ga terminal-overrides ",xterm-256color:Tc"

 # Remap prefix to Control + s
 set -g prefix C-s
 unbind C-b
 bind C-s send-prefix

 set -g focus-events on
 set -sg escape-time 10  # Increased to 10ms for better stability than 0
 set -sg repeat-time 600
 set -g history-limit 99999

 # Mouse support
 set -g mouse on
 set-option -s set-clipboard off
 unbind -T copy-mode-vi MouseDragEnd1Pane # Don't exit copy mode when dragging

 # Indexing
 set -g base-index 1
 setw -g pane-base-index 1
 set -g renumber-windows on # Automatically renumber windows when one is closed

 # ==========================================
 # 2. Key Bindings
 # ==========================================

 # Reload config
 unbind r
 bind r source-file ~/.tmux.conf \; display "Reloaded ~/.tmux.conf"

 # Splitting panes (retains your preference)
 unbind %
 bind | split-window -h -c "#{pane_current_path}"
 bind h split-window -h -c "#{pane_current_path}"
 unbind '"'
 bind - split-window -v -c "#{pane_current_path}"
 bind v split-window -v -c "#{pane_current_path}"

 # Pane resizing
 bind -r H resize-pane -L 5
 bind -r J resize-pane -D 5
 bind -r K resize-pane -U 5
 bind -r L resize-pane -R 5

 # Window Navigation (Alt + Number)
 bind -n M-1 select-window -t 1
 bind -n M-2 select-window -t 2
 bind -n M-3 select-window -t 3
 bind -n M-4 select-window -t 4
 bind -n M-5 select-window -t 5
 bind -n M-6 select-window -t 6
 bind -n M-7 select-window -t 7
 bind -n M-8 select-window -t 8
 bind -n M-9 select-window -t 9

 # Search tmux session with fzf
 bind C-j split-window -v "tmux list-sessions | sed -E 's/:.*$//' | grep -v \"^$(tmux display-message -p '#S')\$\" | fzf --reverse | xargs tmux switch-client -t"

 # Restoring Clear Screen (C-l) since vim-tmux-navigator overrides it
 bind C-l send-keys 'C-l'

 # ==========================================
 # 3. Copy Mode (Vi Style)
 # ==========================================
 setw -g mode-keys vi
 set -g status-keys vi

 unbind [
 bind Escape copy-mode
 unbind p
 bind p paste-buffer

 bind-key -T copy-mode-vi v send -X begin-selection
 # Native macOS clipboard support (no reattach-to-user-namespace needed)
 bind-key -T copy-mode-vi y send -X copy-pipe-and-cancel "pbcopy"
 bind-key -T copy-mode-vi Enter send -X copy-pipe-and-cancel "pbcopy"

 # ==========================================
 # 4. Plugins (TPM)
 # ==========================================
 set -g @plugin 'tmux-plugins/tpm'
 set -g @plugin 'christoomey/vim-tmux-navigator'
 set -g @plugin 'tmux-plugins/tmux-resurrect'
 set -g @plugin 'tmux-plugins/tmux-continuum'
 set -g @plugin 'dracula/tmux'

 # --- Plugin Settings ---
 set -g @resurrect-capture-pane-contents 'on'
 set -g @continuum-restore 'on'

 # Dracula Theme Settings (Overrides manual status bar code)
 set -g status-position top
 set -g @dracula-show-powerline true
 set -g @dracula-fixed-location "Shanghai"
 set -g @dracula-plugins "weather"
 set -g @dracula-show-fahrenheit false
 set -g @dracula-show-flags true
 set -g @dracula-show-left-icon session

 # ==========================================
 # 5. Initialization (MUST BE LAST)
 # ==========================================
 run '~/.tmux/plugins/tpm/tpm'

4. Install Berkeley Mono Font

Note: Berkeley Mono is a paid typeface and cannot be downloaded automatically.

  1. Purchase/Download: Get the font files from the official Berkeley Graphics site.
  2. Install in Windows: Double-click the .ttf files and click Install.

    Important: Alacritty runs on Windows, so the font must be installed in Windows, not just WSL.

  3. Update Alacritty Config: Edit %APPDATA%\alacritty\alacritty.toml: 
    [font]
normal = { family = "Berkeley Mono", style = "Regular" }
size = 12.0

Part 2: Install AI CLI Tools

These tools require Node.js. Install a recent version in WSL using nvm (recommended over apt to avoid permission issues).

Prerequisite: Install Node.js

# Install NVM
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash
source ~/.bashrc

# Install Node.js (LTS)
nvm install --lts

1. Install Claude Code (Anthropic)

Claude Code provides a CLI that is “tmux-aware”.

  1. Install: 
    npm install -g @anthropic-ai/claude-code

  2. Authenticate: Run claude in the terminal. It will provide a link to authenticate via the browser.

  3. Tmux Features: Claude Code can read other tmux panes. You can reference them in prompts like “fix the error in tmux pane 1”.

2. Install Gemini CLI (Google)

  1. Install: 
    npm install -g @google/gemini-cli
  2. Authenticate: Run gemini. It will prompt you to log in with your Google account.

3. Install Codex CLI (OpenAI)

Note: “Codex” often refers to the model powering Copilot, but OpenAI maintains a CLI tool.

  1. Install: 
    npm install -g @openai/codex
  2. Setup: You will need an OpenAI API key. Set it in your environment or when prompted. 
    export OPENAI_API_KEY="your-api-key-here"

Part 3: Usage Guide

  1. Launch: Open Alacritty. It enters WSL automatically.
  2. Start Tmux: 
    tmux new -s ai-dev

Workflow

  • Split Panes: Press Ctrl+s then h (vertical split) or v (horizontal split).

Run Tools

  • Pane 1: Run your code/server.
  • Pane 2: Run claude or gemini.

Context Awareness: When using claude inside tmux, it can inspect errors or logs visible in your other panes, making debugging faster.