Tmux the Terminal Emulator

The terminal multiplexer, tmux, is a software application that helps manage multiple terminal connections.

Some of the major features

Connect and display multiple sessions in the same terminal window.
Issue keystrokes to each open session. Install software on multiple servers simultaneously.
Detach sessions, allow them to continue running, and reattach later.

Tmux is a program that lives in your terminal and allows you to work on multiple things at once.

Basics

TERMINOLOGY

WORKFLOW

Client → Server → Session → Window → Panes

A client(you) connects to a server(local machine or remote). A tmux service is running in the background on that server and will do the magic of handling session/window management. The user then creates a new tmux session to do some work. Each tmux session contains a Window object (but there can be many) and within each Window, there are one (or many) panes.

From Faster command line workflow

SESSION

Tmux requires a session. All output is captured in a session. All sessions are managed by the session manager.

WINDOW

A windows is attached to a tmux session and a window contains one or more panes. You can detach and reattach windows.

PANE

A new terminal window under a given tmux window.

PREFIX KEY

The prefix key indicates you want to execute a tmux command. The default is control-b. You can change the prefix key, if you wish.

Listing all tmux windows: press control-b and then press ‘w’.

# Enter command-mode:
ctrl-b

# Enter text command-mode:
ctrl-b :

# Exit command-mode:
esc

# List command-mode shortcuts:
ctrl-b ?

INSTALLATION

# osx
brew install tmux

#debian
sudo apt-get install tmux

There’s windows support. Apparently Windows 10+ comes with bash.

USAGE

ATTACH TO EXISTING TMUX SESSION OR CREATE A NEW ONE

tmux attach || tmux

CREATE NEW TMUX SESSION WITH NAME MY-BUILD

tmux new-session -s my-build

SHOW ALL SESSIONS

ctl-b w

RENAME YOUR SESSION

ctl-b ,

CREATE NEW SESSION

ctl-b c

CREATE NEW PANES

ctl-b %

REARRANGE PANES

ctl-b space

NAVIGATION

ctl-b arrow-keys

ISSUE COMMANDS TO ALL PANES

# enable
ctl-b :
setw synchronize-panes on

# disable
ctl-b :
setw synchronize-panes off

Demo

For the demo we'll run three separate ubuntu docker containers, connect to each of them in a separate pane, and install java simultaneously on each container.

# download ubuntu docker image
docker pull ubuntu

# start 3 distinct containers from the ubuntu image
docker run -h tmux-test-1 --name tmux-test-1 \
  -d --rm -t ubuntu:latest

docker run -h tmux-test-2 --name tmux-test-2 \
  -d --rm -t ubuntu:latest

docker run -h tmux-test-3 --name tmux-test-3 \
  -d --rm -t ubuntu:latest

Now we'll create the tmux session, window, and 3 panes. One pane for each docker container we want to configure.

# see if there are any existing tmux sessions
tmux ls

# start a tmux session
tmux new -s docker-configure-session

# create a second pane
ctl-b "

# navigate between the panes
ctl-b down-arrow
ctl-b up-arrow

# create a third pane
ctl-b "

# rearrange the panes vertically instead of horizontally
ctl-b space
# can do more ctl-b space to try different layouts

# connect to each docker container. one in each pane.
docker exec -it tmux-test-1 /bin/bash

docker exec -it tmux-test-2 /bin/bash

docker exec -it tmux-test-3 /bin/bash

# tell tmux to issue keystrokes to all panes
ctl-b : setw synchronize-panes on

# make sure it works
clear
whoami
uname -a

# each pane should have a different hostname

# update ubuntu package manager
apt-get update
clear

# install java
apt-get install openjdk-11-jdk
y

# test

java -version

If you have any problems, contact me on X at https://x.com/mleitz1