tmux

or how to organize your terminal sessions

tmux

Terminal Multiplexer

Multiplexer?

[...] access multiple separate login sessions inside a single terminal window, or detach and reattach sessions from a terminal.

It is a wrapper that allows multiple text programs to run at the same time, and provides features that allow the user to use the programs within a single interface productively.

But why?

What's wrong with that?

Hard to find the exact project you want inside of multiple terminal processes with same process name

Can't hide / close terminal process without killing all processes within it

Multiple long running processes needed for a project (e.g. server, console, sidekiq, weback) need to be started manually

How does TMux help?

Organize your projects into named sessions, windows and panes that run in the same parent process

Script tmux to bootstrap your projects

Run long-living processes in the background with sessions

Excellent integration with Vim, if you're using it

Terminology

Sessions
Windows <=> Tabs
Panes <=> Splits

Terminology

Prefix key - C-b (default), C-a (alternative)

Shortcut example: prefix-c

Mentally replace all occurences of 'prefix' with C-b, C-a or whatever you'd like to use as the prefix key

Session

A named collection of terminals under the management of tmux

Keep completely seperated working environments

Easily create new and destroy existing sessions

Processes continue to run in the background when a session is not in focus

Working with sessions

prefix :new -t session_name<CR> - New named session

prefix-s - List all sessions

prefix :kill-session [-t session_name]<CR> - Kill current session or target session

prefix-$ - Rename current session

Tmux Sessionist

Provides convenient shortcuts for managing tmux sessions

prefix-C - Create new named session

prefix-S - Jump to previous session

prefix-X - Kill attached session

And a couple of more things...

Attaching and detaching sessions

You can detach from a session at any time, and the sesssion continues to run in the background

prefix-d - detach session

tmux attach -t session-name

Tmux sessions and SSH

Doing your work in a tmux session on a remote server will ensure you don't lose it your connection drops

Multiple clients can attach to the same session, so you can do easy remote pair programming!

Windows

Equivalent to tabs in terminal emulators

Useful for organizing processes within the same project

Working with windows

prefix-c - Create new window
prefix-p / prefix-n - Previous and next window
prefix-, - Rename current window
prefix-& - Kill current window

Panes

Equivalent to splits in terminal emulators

Useful for running processes that require the same context (e.g. rails server and rails console)

Working with panes

prefix-% - Vertical split
prefix-" - Horizontal split
prefix-x / Ctrl-d - Kill current pane

Zoom pane

Expands the pane to fill the full size of your tmux window

Incredibly useful if you want to focus on something temporarily

prefix-z

Configuring tmux

~/.tmux.conf

# Set prefix to C-a
set -g prefix C-a
unbind C-b
bind C-a send-prefix

# Bind prefix-R to reload configuration
bind R source-file '~/.tmux.conf' \; display-message "Tmux reloaded!"

# Enable mouse
set-option -g -q mouse on

# Use C-h/j/k/l to switch panes
is_vim='echo "#{pane_current_command}" | grep -iqE "(^|\/)g?(view|n?vim?)(diff)?$"'
bind -n C-h if-shell "$is_vim" "send-keys C-h" "select-pane -L"
bind -n C-j if-shell "$is_vim" "send-keys C-j" "select-pane -D"
bind -n C-k if-shell "$is_vim" "send-keys C-k" "select-pane -U"
bind -n C-l if-shell "$is_vim" "send-keys C-l" "select-pane -R"

Scripting Tmux

You can target sessions, windows and even panes through the terminal

Enables automation of starting up project environments

Scripting Tmux

# Caveat: guaranteed not to work...

tmux new-session -A -d -s bmx-api -n editor -c /home/marko/source/butterflymx/bmx-api/
tmux send-keys -t bmx-api 'vim' C-m
tmux new-window -n shell -t bmx-api -c /home/marko/source/butterflymx/bmx-api/
tmux new-window -n webpack -t bmx-api -c /home/marko/source/butterflymx/bmx-api/
tmux split-window -v -t bmx-api:1
tmux split-window -h -t bmx-api:1.1
tmux send-keys -t bmx-api:1.1 'rails s' C-m
tmux send-keys -t bmx-api:1.2 'rails c' C-m
tmux select-window -t bmx-api:0
tmux attach -t bmx-api

Your project bash script

Tmuxinator

Ruby gem that enables you to intuitively build sessions from YAML configuration files

gem install tmuxinator

Tmuxinator

name: bmx-api
root: /home/marko/source/butterflymx/api-rails4

# startup_window: 0

windows:
  - editor: vim
  - shell:
      layout: 4a73,271x70,0,0{135x70,0,0,1,135x70,136,0[135x35,136,0,3,135x34,136,36,5]}
      panes:
        -
        - rails s
        - rails c
  - webpack:

Fetching the scary layout thingy

Arrange your panes in the way you like them

Run prefix :list-windows<CR> to display a list of windows in the current session

Hold shift to select the layout string and copy it over to your YAML file

Plugins - TPM

Tmux plugin manager enables easy plugin installation and management

https://github.com/tmux-plugins/tpm

Sensible

Provides sensible tmux configurations

https://github.com/tmux-plugins/tmux-sensible

Sessionist

Adds convenient shortcuts for working with sessions

https://github.com/tmux-plugins/tmux-sessionist

Resurrect

Persist session between system restarts

https://github.com/tmux-plugins/tmux-resurrect

Continuum

Continous saving of tmux environment and automatic restore on tmux start

Depends on resurrect plugin

https://github.com/tmux-plugins/tmux-continuum

Conclusion

We learned ~80% of what there is to know about tmux

Leverage tmux's sessions to seperate your project workspaces, and windows and panes to organize them

Thanks!

Marko Ivanek

Rails Engineer @ ButterflyMX

Occasional consultant

markoivanek@gmail.com