tmux — Terminal Multiplexer for Persistent SSH Sessions

Why tmux is a sysadmin lifesaver

When connected to a remote server over SSH, closing your laptop, experiencing Wi-Fi drops, or switching networks immediately kills your active shell session. Any long-running script, database migration, or system compilation running in that terminal is abruptly terminated.

tmux (Terminal Multiplexer) solves this by running as a persistent background daemon:

1. Persistent Sessions: Disconnecting from SSH does not terminate your processes; programs continue running on the server.
2. Terminal Tiling: Split a single terminal window into multiple horizontal and vertical panes.
3. Multi-Window Navigation: Switch between full-screen virtual terminal tabs inside a single SSH connection.

Installation

On Debian, Ubuntu, or Raspberry Pi OS:

sudo apt update
sudo apt install -y tmux

1. Managing Sessions: Commands & Flags Breakdown

# 1. Start a brand new session with a memorable name
tmux new -s dev

# 2. List all active background sessions
tmux ls

# 3. Reattach to an existing session
tmux attach -t dev

# 4. Terminate a session completely
tmux kill-session -t dev

Command & flag breakdown

• new -s <name>: Creates a new session. The -s flag assigns a custom human-readable name (e.g. dev, backup, deploy) instead of a random number.
• ls: Lists all currently running tmux sessions, showing the number of windows, creation date, and attached/detached status.
• attach -t <name>: Re-attaches your terminal to a background session. The -t flag specifies the target session name.
• kill-session -t <name>: Shuts down the specified session and gracefully terminates its child shell processes.

2. Detaching safely: Keep programs running

To disconnect from a running session without killing your programs:

1. Press Ctrl + b, release both keys.
2. Press d (detach).

You are returned to your normal shell prompt with the message [detached (from session dev)]. You can now safely close your terminal, shut down your laptop, or disconnect SSH.

When you log back in later, simply type:

tmux attach -t dev

Everything will be exactly where you left it!

3. Essential Keyboard Shortcuts

Inside tmux, all commands begin with the default prefix key: Ctrl + b. Press the prefix first, release it, and then press the action key:

Managing Panes (Splits)

Managing Windows (Tabs)

Scrolling & Copy Mode

Terminal output in tmux doesn't scroll with your mouse wheel by default:

• Press Ctrl+b then [ to enter scroll mode.
• Use arrow keys or Page Up / Page Down to scroll through historical logs.
• Press q to exit scroll mode and return to your live terminal prompt.

4. Enabling Mouse Support in ~/.tmux.conf

Create a configuration file at ~/.tmux.conf to enable mouse clicking between splits, drag-to-resize panes, and mouse wheel scrolling:

cat << 'EOF' > ~/.tmux.conf
# Enable full mouse control (clicking panes, scrolling, resizing)
set -g mouse on

# Increase scrollback history buffer to 10,000 lines
set -g history-limit 10000

# Use 256 colors
set -g default-terminal "screen-256color"
EOF

Reload the configuration inside tmux: Press Ctrl+b then :, type source-file ~/.tmux.conf, and press Enter.