Using tmux for Interactive Commands

Overview

Interactive CLI tools (vim, interactive git rebase, REPLs, etc.) cannot be controlled through standard bash because they require a real terminal. tmux provides detached sessions that can be controlled programmatically via send-keys and capture-pane .

When to Use

Use tmux when:

• Running vim, nano, or other text editors programmatically

• Controlling interactive REPLs (Python, Node, etc.)

• Handling interactive git commands (git rebase -i , git add -p )

• Working with full-screen terminal apps (htop, etc.)

• Commands that require terminal control codes or readline

Don't use for:

• Simple non-interactive commands (use regular Bash tool)

• Commands that accept input via stdin redirection

• One-shot commands that don't need interaction

Quick Reference

Task Command

Start session tmux new-session -d -s <name> <command>

Send input tmux send-keys -t <name> 'text' Enter

Capture output tmux capture-pane -t <name> -p

Stop session tmux kill-session -t <name>

List sessions tmux list-sessions

Core Pattern

Before (Won't Work)

This hangs because vim expects interactive terminal

bash -c "vim file.txt"

After (Works)

Create detached tmux session

tmux new-session -d -s edit_session vim file.txt

Send commands (Enter, Escape are tmux key names)

tmux send-keys -t edit_session 'i' 'Hello World' Escape ':wq' Enter

Capture what's on screen

tmux capture-pane -t edit_session -p

Clean up

tmux kill-session -t edit_session

Implementation

Basic Workflow

• Create detached session with the interactive command

• Wait briefly for initialization (100-500ms depending on command)

• Send input using send-keys (can send special keys like Enter, Escape)

• Capture output using capture-pane -p to see current screen state

• Repeat steps 3-4 as needed

• Terminate session when done

Special Keys

Common tmux key names:

• Enter

• Return/newline

• Escape

• ESC key

• C-c

• Ctrl+C

• C-x

• Ctrl+X

• Up , Down , Left , Right

• Arrow keys

• Space

• Space bar

• BSpace

• Backspace

Working Directory

Specify working directory when creating session:

tmux new-session -d -s git_session -c /path/to/repo git rebase -i HEAD~3

Helper Wrapper

For easier use, see /home/jesse/git/interactive-command/tmux-wrapper.sh :

Start session

/path/to/tmux-wrapper.sh start <session-name> <command> [args...]

Send input

/path/to/tmux-wrapper.sh send <session-name> 'text' Enter

Capture current state

/path/to/tmux-wrapper.sh capture <session-name>

Stop

/path/to/tmux-wrapper.sh stop <session-name>

Common Patterns

Python REPL

tmux new-session -d -s python python3 -i tmux send-keys -t python 'import math' Enter tmux send-keys -t python 'print(math.pi)' Enter tmux capture-pane -t python -p # See output tmux kill-session -t python

Vim Editing

tmux new-session -d -s vim vim /tmp/file.txt sleep 0.3 # Wait for vim to start tmux send-keys -t vim 'i' 'New content' Escape ':wq' Enter

File is now saved

Interactive Git Rebase

tmux new-session -d -s rebase -c /repo/path git rebase -i HEAD~3 sleep 0.5 tmux capture-pane -t rebase -p # See rebase editor

Send commands to modify rebase instructions

tmux send-keys -t rebase 'Down' 'Home' 'squash' Escape tmux send-keys -t rebase ':wq' Enter

Common Mistakes

Not Waiting After Session Start

Problem: Capturing immediately after new-session shows blank screen

Fix: Add brief sleep (100-500ms) before first capture

tmux new-session -d -s sess command sleep 0.3 # Let command initialize tmux capture-pane -t sess -p

Forgetting Enter Key

Problem: Commands typed but not executed

Fix: Explicitly send Enter

tmux send-keys -t sess 'print("hello")' Enter # Note: Enter is separate argument

Using Wrong Key Names

Problem: tmux send-keys -t sess '\n' doesn't work

Fix: Use tmux key names: Enter , not \n

tmux send-keys -t sess 'text' Enter # ✓ tmux send-keys -t sess 'text\n' # ✗

Not Cleaning Up Sessions

Problem: Orphaned tmux sessions accumulate

Fix: Always kill sessions when done

tmux kill-session -t session_name

Or check for existing: tmux has-session -t name 2>/dev/null

Real-World Impact

• Enables programmatic control of vim/nano for file editing

• Allows automation of interactive git workflows (rebase, add -p)

• Makes REPL-based testing/debugging possible

• Unblocks any tool that requires terminal interaction

• No need to build custom PTY management - tmux handles it all