Pane Management

Splitting, resizing, swapping, breaking and joining panes in tmux

Understanding Panes

A pane is a rectangular section within a tmux window. Each pane contains a separate pseudo terminal and can run its own program independently. Panes allow you to view and interact with multiple programs simultaneously within a single window.

Panes are numbered starting from 0 in the order they are created. Each pane has a unique pane ID (like %0, %1) that persists for its lifetime.

Splitting Panes

Basic Splitting

The most common way to create panes is by splitting existing ones:

Horizontal Split

C-b "  # Split into top and bottom panes

Creates two panes stacked vertically (horizontal split line).

Vertical Split

C-b %  # Split into left and right panes

Creates two panes side by side (vertical split line).

Split-Window Command

More control over splitting:

# Split vertically (default)
tmux split-window
tmux splitw

# Split horizontally
tmux split-window -h
tmux splitw -h

# Split in reverse direction (before current pane)
tmux split-window -b
tmux split-window -hb  # Horizontal, before

# Specify pane size
tmux split-window -l 10     # 10 lines
tmux split-window -h -l 40  # 40 columns
tmux split-window -l 30%    # 30% of window

# Full width/height split
tmux split-window -hf  # Full height
tmux split-window -f   # Full width

Creating Panes with Commands

# Run a command in new pane
tmux split-window htop
tmux split-window -h 'tail -f /var/log/syslog'

# Start in specific directory
tmux split-window -c /var/log

# Set environment variable
tmux split-window -e EDITOR=vim

# Create empty pane (no command)
tmux split-window ''

# Forward stdin to empty pane
make 2>&1 | tmux split-window -dI &

The -d flag creates a pane without switching to it, useful in scripts.

Navigating Panes

Quick Navigation

Keys	Action
C-b o	Select next pane in order
C-b ;	Move to previously active pane
C-b Up	Move to pane above
C-b Down	Move to pane below
C-b Left	Move to pane on left
C-b Right	Move to pane on right
C-b q	Display pane numbers
C-b q 0-9	Display pane numbers, then select

Select-Pane Command

# Select pane by ID
tmux select-pane -t %2

# Navigate directionally
tmux select-pane -U  # Up
tmux select-pane -D  # Down
tmux select-pane -L  # Left
tmux select-pane -R  # Right

# Select last active pane
tmux select-pane -l

# Select pane using special tokens
tmux select-pane -t '{top}'         # Top pane
tmux select-pane -t '{bottom}'      # Bottom pane
tmux select-pane -t '{left}'        # Leftmost pane
tmux select-pane -t '{right}'       # Rightmost pane
tmux select-pane -t '{top-left}'    # Top-left pane
tmux select-pane -t '{bottom-right}' # Bottom-right pane
tmux select-pane -t '{up-of}'       # Pane above active
tmux select-pane -t '{down-of}'     # Pane below active
tmux select-pane -t '{left-of}'     # Pane left of active
tmux select-pane -t '{right-of}'    # Pane right of active

Resizing Panes

Interactive Resizing

1. Arrow Keys (Fine)
2. C-b C-Up      # Resize up by 1 cell
   C-b C-Down    # Resize down by 1 cell
   C-b C-Left    # Resize left by 1 cell
   C-b C-Right   # Resize right by 1 cell
   

3. Alt+Arrow Keys (Coarse)
4. C-b M-Up      # Resize up by 5 cells
   C-b M-Down    # Resize down by 5 cells
   C-b M-Left    # Resize left by 5 cells
   C-b M-Right   # Resize right by 5 cells
   

Resize-Pane Command

# Resize by specific amount
tmux resize-pane -U 5   # Up 5 lines
tmux resize-pane -D 10  # Down 10 lines
tmux resize-pane -L 20  # Left 20 columns
tmux resize-pane -R 15  # Right 15 columns

# Resize to absolute size
tmux resize-pane -x 80  # Set width to 80 columns
tmux resize-pane -y 24  # Set height to 24 lines

# Use percentage
tmux resize-pane -x 50%  # Half window width
tmux resize-pane -y 30%  # 30% of window height

# Target specific pane
tmux resize-pane -t %3 -R 10

Zoom Pane

Temporarily make a pane fill the entire window:

C-b z  # Toggle zoom on current pane

tmux resize-pane -Z  # Command form

Zoomed panes are marked with a Z flag in the status line. Press C-b z again to unzoom.

Swapping and Moving Panes

Swapping Panes

Exchange two panes:

C-b {  # Swap with previous pane
C-b }  # Swap with next pane

# Command form
tmux swap-pane -U  # Swap with previous
tmux swap-pane -D  # Swap with next

# Swap specific panes
tmux swap-pane -s %1 -t %3

# Swap without changing active pane
tmux swap-pane -d -t %2

# Use marked pane as source
tmux select-pane -m     # Mark pane
tmux swap-pane          # Swap with marked

Rotating Panes

Rotate all panes in the window:

C-b C-o  # Rotate panes forwards
C-b M-o  # Rotate panes backwards

tmux rotate-window     # Rotate down/right
tmux rotate-window -U  # Rotate up/left

Breaking Panes Out

Turn a pane into its own window:

C-b !  # Break pane into new window

# Command with options
tmux break-pane

# Create window at specific index
tmux break-pane -t :3

# Give new window a name
tmux break-pane -n logs

# Insert before (-b) or after (-a)
tmux break-pane -a -t :2

# Don't switch to new window
tmux break-pane -d

Joining Panes

Move a pane from one window to another:

# Join pane from another window
tmux join-pane -s :2.0  # Join pane 0 from window 2

# Specify destination
tmux join-pane -s :1 -t :3.1  # Join to specific pane

# Split direction
tmux join-pane -h -s :2  # Join horizontally
tmux join-pane -v -s :2  # Join vertically (default)

# Join before destination
tmux join-pane -b -s :2

# Specify size
tmux join-pane -l 30% -s :2

# Use marked pane
tmux select-pane -m     # Mark source pane
tmux join-pane          # Join marked pane

Marking panes is useful for moving panes between windows without typing IDs. Mark with C-b m, clear mark with C-b M.

Killing Panes

Interactive Kill

C-b x  # Kill current pane (prompts for confirmation)

Command Line Kill

# Kill current pane
tmux kill-pane

# Kill specific pane
tmux kill-pane -t %3

# Kill all panes except current
tmux kill-pane -a
tmux killp -a -t %2  # All except pane %2

Pane Layouts

Preset Layouts

Quickly arrange panes:

C-b Space    # Cycle to next layout
C-b M-1      # even-horizontal
C-b M-2      # even-vertical  
C-b M-3      # main-horizontal
C-b M-4      # main-horizontal-mirrored
C-b M-5      # main-vertical
C-b M-6      # main-vertical-mirrored
C-b M-7      # tiled

# Command form
tmux select-layout even-horizontal
tmux select-layout main-vertical

# Next/previous layout
tmux next-layout
tmux previous-layout

Layout Descriptions

even-horizontal

Panes spread evenly from left to right across the window.

even-vertical

Panes spread evenly from top to bottom.

main-horizontal

Large pane at top, remaining panes spread left to right at bottom. Control main pane height with main-pane-height option.

main-vertical

Large pane on left, remaining panes spread top to bottom on right. Control main pane width with main-pane-width option.

tiled

Panes spread evenly in both rows and columns.

Custom Layouts

# Save current layout
tmux display-message -p '#{window_layout}'
# Output: bb62,159x48,0,0{79x48,0,0,79x48,80,0}

# Restore saved layout
tmux select-layout 'bb62,159x48,0,0{79x48,0,0,79x48,80,0}'

# Undo layout change
tmux select-layout -o

# Spread panes evenly
tmux select-layout -E

Pane Synchronization

Send input to multiple panes simultaneously:

# Enable synchronization for current window
tmux set-option -w synchronize-panes on

# Disable
tmux set-option -w synchronize-panes off

# Toggle with key binding
bind-key S set-option -w synchronize-panes

When synchronize-panes is on, all input goes to every pane in the window. This only affects panes that are not in any special mode (like copy mode).

Pane Information and Display

Display Panes

C-b q     # Show pane numbers briefly
C-b q 0-9 # Show numbers and switch to pane

# Display panes command
tmux display-panes
tmux display-panes -d 5000  # Show for 5 seconds
tmux display-panes -d 0     # Show until keypress

List Panes

# List panes in current window
tmux list-panes
tmux lsp

# List panes in specific window
tmux list-panes -t :2

# List all panes in session
tmux list-panes -s

# List all panes on server
tmux list-panes -a

# Custom format
tmux list-panes -F "Pane #{pane_index}: #{pane_title}"

# Filter panes
tmux list-panes -f '#{==:#{pane_active},1}'

# Sort panes
tmux list-panes -O index   # By index
tmux list-panes -O size    # By area
tmux list-panes -O creation # By creation time

Pane Format Variables

Useful format variables for panes:

# #{pane_id}              - Unique pane ID (%0, %1, etc.)
# #{pane_index}           - Pane index in window
# #{pane_current_command} - Current command
# #{pane_current_path}    - Current working directory
# #{pane_title}           - Pane title
# #{pane_pid}             - PID of pane process
# #{pane_active}          - 1 if pane is active
# #{pane_width}           - Pane width
# #{pane_height}          - Pane height
# #{pane_left}            - Left position
# #{pane_top}             - Top position
# #{pane_in_mode}         - 1 if pane is in mode
# #{pane_synchronized}    - 1 if synchronized

Pane Titles and Borders

Setting Pane Titles

# Set pane title
tmux select-pane -T "Database Console"

# From shell with escape sequence
printf '\033]2;My Title\033\\'

Pane Border Styles

# Pane border style
set-option -g pane-border-style fg=blue

# Active pane border
set-option -g pane-active-border-style fg=green,bold

# Display pane numbers/indicators
set-option -g display-panes-colour blue
set-option -g display-panes-active-colour red
set-option -g display-panes-time 2000

Pane Border Status

Show information in pane borders:

# Enable border status
set-option -g pane-border-status top
set-option -g pane-border-status bottom
set-option -g pane-border-status off

# Format for border status
set-option -g pane-border-format " #{pane_index} #{pane_current_command} "
set-option -g pane-border-format " [ #T ] #{pane_current_path} "

Marking Panes

Mark a pane as the default target for operations:

C-b m  # Mark current pane
C-b M  # Clear marked pane

# Commands that use marked pane
tmux join-pane    # Join marked pane to current window
tmux swap-pane    # Swap with marked pane
tmux swap-window  # Swap window containing marked pane

# Target marked pane explicitly
tmux select-pane -t '{marked}'

Only one pane can be marked at a time. Marking a new pane clears the previous mark.

Enabling and Disabling Panes

Control pane input:

# Disable input to pane (read-only)
tmux select-pane -d

# Enable input to pane
tmux select-pane -e

# Toggle with last-pane
tmux last-pane -e  # Enable input
tmux last-pane -d  # Disable input

Advanced Pane Management

Capture Pane Content

# Capture visible content
tmux capture-pane

# Capture to stdout
tmux capture-pane -p

# Capture with history
tmux capture-pane -S -1000  # Last 1000 lines

# Capture specific range
tmux capture-pane -S 0 -E 50  # Lines 0-50

# Save to file
tmux capture-pane -p > output.txt

# Include escape sequences (colors/attributes)
tmux capture-pane -ep

# Save to buffer
tmux capture-pane -b mybuffer

Pipe Pane Output

Redirect pane output to a command:

# Pipe to file
tmux pipe-pane -o 'cat >>~/output.log'

# Pipe with format expansion
tmux pipe-pane -o 'cat >>~/tmux-#S-#I-#P.log'

# Toggle with -o
bind-key C-p pipe-pane -o 'cat >>~/output.#I-#P'

# Pipe input to pane
tmux pipe-pane -I 'command-that-generates-input'

# Stop piping
tmux pipe-pane

Respawn Pane

Restart a pane that has exited:

# Respawn with original command
tmux respawn-pane

# Respawn with new command
tmux respawn-pane 'htop'

# Kill existing process first
tmux respawn-pane -k

# Change directory
tmux respawn-pane -c /var/log

Practical Examples

Development Layout

#!/bin/bash
# Create a development layout

tmux split-window -h -p 30
tmux select-pane -t 0
tmux split-window -v -p 15

# Pane 0: Editor (top-left, 70% width, 85% height)
# Pane 1: Terminal (bottom-left, 70% width, 15% height)  
# Pane 2: Logs (right, 30% width, full height)

tmux select-pane -t 0
tmux send-keys 'vim' C-m

tmux select-pane -t 2
tmux send-keys 'tail -f log/development.log' C-m

Monitoring Dashboard

# Create 2x2 grid
tmux split-window -h
tmux split-window -v
tmux select-pane -t 0
tmux split-window -v

# Top-left: CPU
tmux send-keys -t 0 'htop' C-m

# Bottom-left: Disk
tmux send-keys -t 1 'watch df -h' C-m

# Top-right: Network
tmux send-keys -t 2 'iftop' C-m

# Bottom-right: Logs
tmux send-keys -t 3 'tail -f /var/log/syslog' C-m

Custom Key Bindings

# Better split commands
bind | split-window -h -c "#{pane_current_path}"
bind - split-window -v -c "#{pane_current_path}"

# Quick pane selection
bind -n M-Left select-pane -L
bind -n M-Right select-pane -R
bind -n M-Up select-pane -U
bind -n M-Down select-pane -D

# 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

# Break pane to new window
bind B break-pane -d

# Join pane from other window
bind j command-prompt -p "join pane from:" "join-pane -s '%%'"