tmux and screen Tutorial: Keep Linux Sessions Alive, Split Panes and Windows

By Ravindra Bagale, trainer LinkedIn Last updated: 25 October 2026

You start a 2-hour database migration over SSH, your Wi-Fi drops, and the job dies with the session. tmux and GNU screen stop that from happening. They keep your terminal running on the server, so you can detach, close your laptop, and attach again later. tmux also splits one screen into many windows and panes. We learn each command and each key one by one.

What you'll learn in this chapter

Start, name, list and attach tmux sessions
Detach and kill sessions safely
Use windows and split panes
Scroll and copy with copy mode
Configure tmux with .tmux.conf and send-keys
Use GNU screen basics

1. An everyday example: the pressure cooker on the gas

Why do we need this?

You put dal in the pressure cooker and go to answer the door. The cooker keeps cooking without you. You come back, check the whistles, and continue. If you had to hold the cooker with your hand the whole time, any interruption would ruin the dal.

What is it?

Cooker on the gas = tmux session on the server. Walking away = detach (Ctrl+b d). Coming back = tmux attach. Holding it by hand = a plain SSH session that dies when the network drops.

How to do it (step by step)

A reboot of the server ends tmux sessions too; they live in memory.

2. Install tmux and the prefix key

Why do we need this?

Every tmux shortcut starts with a prefix, so it does not clash with your programs.

What is it?

Install: sudo dnf install tmux or sudo apt install tmux. The prefix is Ctrl+b: press Ctrl and b together, let go, then press the next key. In this chapter 'Ctrl+b d' means prefix then d. Ctrl+b ? lists all keys.

How to do it (step by step)

Install.

sudo dnf install -y tmux && tmux -V

Output:

tmux 3.2a

What it means: Version 3.x is common.

See all key bindings.

tmux list-keys | head -3

Output:

bind-key    -T copy-mode    C-Space    send-keys -X begin-selection
bind-key    -T prefix       d          detach-client
bind-key    -T prefix       c          new-window

What it means: prefix d = detach.

3. tmux new -s: start a named session

Why do we need this?

Names like 'migrate' or 'deploy' tell you what each session is for when you come back later.

What is it?

tmux new -s NAME (same as new-session -s). Plain tmux gives a number name (0, 1...). -d starts it detached. You can give a command to run: tmux new -d -s NAME 'command'. The green status bar at the bottom means you are inside tmux.

How to do it (step by step)

Start a session for a migration.

tmux new -s migrate

Output:

[migrate] 0:bash*                 "web1" 14:30 25-Oct-26

What it means: Status bar: session, window, host, time.

Start one in the background.

tmux new -d -s backup 'sudo /usr/local/bin/backup.sh'

Output:

(no output)

What it means: Runs without you attached.

Am I inside tmux?

echo "${TMUX:-not in tmux}"

Output:

/tmp/tmux-1000/default,4120,0

What it means: TMUX is set inside.

4. Detach: Ctrl+b d

Why do we need this?

Detaching leaves everything running while you log out, travel or switch machines.

What is it?

Ctrl+b d detaches. tmux detach does the same from the command line. Closing the SSH window or a network drop has the same effect: the session keeps running.

How to do it (step by step)

Inside tmux, start the job.

./migrate.sh --all

Output:

Migrating table 1/240 ...

What it means: It will take a while.

Press Ctrl+b then d.

Ctrl+b d

Output:

[detached (from session migrate)]

What it means: You are back in the normal shell.

Log out safely.

exit

Output:

logout
Connection to 15.0.0.10 closed.

What it means: migrate.sh keeps running.

5. tmux ls and attach -t

Why do we need this?

After you reconnect, you need to see what sessions exist and get back into the right one.

What is it?

tmux ls (list-sessions) shows sessions, window count and whether attached. tmux attach -t NAME (or tmux a -t NAME) joins it. tmux attach alone joins the last one. -d detaches other clients that are attached.

How to do it (step by step)

List.

tmux ls

Output:

backup: 1 windows (created Sun Oct 25 14:31:02 2026)
migrate: 1 windows (created Sun Oct 25 14:30:10 2026)

What it means: Both still alive.

Attach.

tmux attach -t migrate

Output:

Migrating table 187/240 ...

What it means: Right where it was.

No server yet.

tmux ls

Output:

no server running on /tmp/tmux-1000/default

What it means: No sessions exist.

6. kill-session, kill-server and rename

Why do we need this?

Old sessions waste memory and confuse people. Clean them when work is done.

What is it?

tmux kill-session -t NAME ends one (and the programs in it). tmux kill-server ends all. exit in the last pane also ends the session. tmux rename-session -t old new, or Ctrl+b $, renames.

How to do it (step by step)

Rename.

tmux rename-session -t backup nightly && tmux ls | head -1

Output:

migrate: 1 windows (created Sun Oct 25 14:30:10 2026)

What it means: Sorted by name.

Kill one.

tmux kill-session -t nightly && tmux ls

Output:

migrate: 1 windows (created Sun Oct 25 14:30:10 2026)

What it means: Only migrate left.

Kill all.

tmux kill-server; tmux ls

Output:

no server running on /tmp/tmux-1000/default

What it means: Everything closed. Be sure first.

7. Windows: Ctrl+b c, n, p, number, ,

Why do we need this?

One session can hold many full-screen windows: logs in one, editor in another, a shell in a third.

What is it?

Ctrl+b c creates a window. Ctrl+b n next, Ctrl+b p previous, Ctrl+b 0..9 jump. Ctrl+b , renames. Ctrl+b w shows a chooser. Ctrl+b & closes the window (asks). The status bar shows the * on the current one.

How to do it (step by step)

Create and name windows.

Ctrl+b c   then Ctrl+b ,  type: logs

Output:

[ops] 0:bash- 1:logs*

What it means: Two windows now.

Jump.

Ctrl+b 0

Output:

[ops] 0:bash* 1:logs-

What it means: Back to window 0.

Same from the command line.

tmux new-window -t ops -n editor

Output:

[ops] 0:bash 1:logs 2:editor*

What it means: Good for scripts.

8. Panes: Ctrl+b % and ", arrows, z, x

Why do we need this?

See logs and the shell side by side while you fix something.

What is it?

Ctrl+b % splits left/right. Ctrl+b " splits top/bottom. Ctrl+b arrow moves between panes. Ctrl+b z zooms one pane full screen and back. Ctrl+b x closes a pane. Ctrl+b Ctrl+arrow resizes. Ctrl+b space cycles layouts. Ctrl+b q shows numbers.

Keys	Action
Ctrl+b %	Split left/right
Ctrl+b "	Split top/bottom
Ctrl+b arrow	Move to pane
Ctrl+b z	Zoom toggle
Ctrl+b x	Close pane
Ctrl+b space	Next layout

How to do it (step by step)

Split and follow logs.

Ctrl+b %   then in the right pane: journalctl -fu shop-api

Output:

(left: shell, right: live logs)

What it means: Fix on the left, watch on the right.

Zoom to read.

Ctrl+b z

Output:

(right pane fills the screen; Z in the status bar)

What it means: Press again to unzoom.

From a script.

tmux split-window -h -t ops 'htop'

Output:

(new pane with htop)

What it means: -h = side by side.

9. Copy mode: scroll and copy (Ctrl+b [)

Why do we need this?

The mouse wheel does not scroll tmux by default. You need to read old output and copy error lines.

What is it?

Ctrl+b [ enters copy mode. Use arrows, PgUp/PgDn; / or ? to search. Space starts a selection, Enter copies it (emacs keys default) or v/y with vi mode. Ctrl+b ] pastes. q leaves. history-limit sets how many lines are kept.

How to do it (step by step)

Scroll up.

Ctrl+b [   then PgUp

Output:

[0/1532] shown at top right

What it means: 1532 lines of history.

Search for an error.

Ctrl+b [   then ?  type ERROR  Enter

Output:

(cursor jumps to the last ERROR)

What it means: n for the next match.

Copy and paste.

Space ... move ... Enter, then Ctrl+b ]

Output:

(selected text pasted at the prompt)

What it means: Copy without the mouse.

10. ~/.tmux.conf: make tmux yours

Why do we need this?

A few settings make tmux much easier: mouse, bigger history, easier splits, windows starting at 1.

What is it?

Put lines in ~/.tmux.conf. set -g mouse on enables scrolling, clicking and resizing. set -g history-limit 50000. set -g base-index 1. bind | split-window -h. Reload: tmux source-file ~/.tmux.conf.

How to do it (step by step)

Write a good starter config.

cat > ~/.tmux.conf <<'X'
set -g mouse on
set -g history-limit 50000
set -g base-index 1
setw -g pane-base-index 1
bind | split-window -h -c '#{pane_current_path}'
bind - split-window -v -c '#{pane_current_path}'
bind r source-file ~/.tmux.conf \; display 'reloaded'
X

Output:

(no output)

What it means: Easy-to-remember splits.

Reload.

tmux source-file ~/.tmux.conf

Output:

(status shows nothing or 'reloaded' with Ctrl+b r)

What it means: No need to restart.

Check a value.

tmux show -g history-limit

Output:

history-limit 50000

What it means: Applied.

11. send-keys and scripted layouts

Why do we need this?

Every morning you open the same 4 panes. A script can build them in one second.

What is it?

tmux send-keys -t SESSION:WINDOW.PANE 'command' Enter types into a pane. Combine new -d, split-window, select-layout tiled and attach to build a workspace. has-session -t NAME tests if it exists.

How to do it (step by step)

A one-shot ops workspace.

tmux has-session -t ops 2>/dev/null || {
 tmux new -d -s ops -n main
 tmux split-window -h -t ops
 tmux send-keys -t ops:main.1 'journalctl -fu nginx' Enter
 tmux split-window -v -t ops:main.1
 tmux send-keys -t ops:main.2 'htop' Enter
}
tmux attach -t ops

Output:

(three panes: shell, nginx logs, htop)

What it means: Same layout every day.

Send to a running session.

tmux send-keys -t migrate 'echo still here' Enter

Output:

(the text runs inside migrate)

What it means: Without attaching.

Why do we need this?

A senior can watch and help a junior live on the same terminal, without screen sharing software.

What is it?

Two people logged in as the same user can both run tmux attach -t NAME and see the same thing. For different users, use a shared socket: tmux -S /tmp/pair new -s pair, chgrp a common group, chmod 770, and the other runs tmux -S /tmp/pair attach. attach -r is read-only.

How to do it (step by step)

Start a shared socket.

tmux -S /tmp/pair new -d -s pair && chgrp devops /tmp/pair && chmod 770 /tmp/pair

Output:

(no output)

What it means: Only the devops group can join.

Teammate watches read-only.

tmux -S /tmp/pair attach -r -t pair

Output:

(same screen, cannot type)

What it means: Safe for training.

13. GNU screen basics

Why do we need this?

Older servers and some appliances have screen but not tmux. The ideas are the same.

What is it?

Prefix is Ctrl+a. screen -S NAME starts. Ctrl+a d detaches. screen -ls lists. screen -r NAME reattaches (-d -r to steal it). Ctrl+a c new window, Ctrl+a n/p next/prev, Ctrl+a " list, Ctrl+a S split, Ctrl+a Tab move, Ctrl+a [ copy mode, Ctrl+a k kill. screen -L logs output to screenlog.0.

Task	tmux	screen
New named	tmux new -s x	screen -S x
Detach	Ctrl+b d	Ctrl+a d
List	tmux ls	screen -ls
Attach	tmux attach -t x	screen -r x
New window	Ctrl+b c	Ctrl+a c

How to do it (step by step)

Start and detach.

screen -S upload   then Ctrl+a d

Output:

[detached from 5120.upload]

What it means: Same idea as tmux.

List.

screen -ls

Output:

There is a screen on:
	5120.upload	(Detached)
1 Socket in /run/screen/S-ravi.

What it means: Detached and alive.

Reattach.

screen -r upload

Output:

(back inside)

What it means: Use -d -r if it says Attached.

Log everything to a file.

screen -L -S job ./long.sh

Output:

(output also in screenlog.0)

What it means: Proof of what happened.

14. Real examples from many industries

Why do we need this?

The same Linux skill shows up in every kind of company. Seeing it in many places helps you remember it.

What is it?

Each row is a made-up team. It shows who uses this and how.

How to do it (step by step)

Team and city	How they use it	Command
Siddharth, bank DBA, Pune	Runs long migrations inside tmux	`tmux new -s migrate`
Grace, SRE, Seattle	Scripted 4-pane on-call workspace	`tmux send-keys -t ops 'htop' Enter`
Ahmed, telecom NOC, Cairo	Uses screen on old network boxes	`screen -r console`
Sofia, ML lab, Milan	Keeps GPU training alive overnight	`tmux new -d -s train 'python train.py'`
Hiro, game ops, Tokyo	Read-only shared session for trainees	`tmux -S /tmp/pair attach -r`
Meera, college, Satara	Splits panes to teach logs and shell together	`Ctrl+b %`

15. Common errors and how to fix them

Why do we need this?

Everyone hits these errors. Knowing the cause saves hours.

What is it?

Read the exact message first. Then match it to a row below.

How to do it (step by step)

Error you see	Why it happens	How to fix
`no server running on /tmp/tmux-1000/default`	No sessions exist (or a reboot killed them)	Start a new one. `tmux new -s work`
`can't find session: migrate`	Wrong name, or it ended	List the names. `tmux ls`
`sessions should be nested with care, unset $TMUX to force`	You ran tmux inside tmux	Switch with Ctrl+b s or detach first. `tmux switch-client -t migrate`
`duplicate session: migrate`	A session with that name exists	Attach to it or pick another name. `tmux attach -t migrate`
`open terminal failed: missing or unsuitable terminal: xterm-kitty`	Server does not know your TERM	Use a common TERM. `TERM=xterm-256color tmux`
`Mouse wheel scrolls the shell history, not the output`	Mouse mode is off	Turn it on or use copy mode. `tmux set -g mouse on`
`There is a screen on: ... (Attached) / screen -r fails`	Session still attached elsewhere	Detach the other and attach. `screen -d -r upload`
`Job died after closing the laptop`	It was not inside tmux/screen	Always start long jobs inside tmux. `tmux new -s job`
`Colours look wrong in tmux`	TERM inside tmux not 256-colour	Set default-terminal. `set -g default-terminal 'tmux-256color'`
`error connecting to /tmp/pair (Permission denied)`	Shared socket permissions	chgrp and chmod 770 the socket. `chmod 770 /tmp/pair`

16. Troubleshooting step by step

Why do we need this?

If you cannot get back to your work, find the tmux server, then the session, then the pane.

What is it?

Go top to bottom. Stop at the first step that shows the problem.

How to do it (step by step)

Is tmux still running?

pgrep -a tmux

List sessions.

tmux ls

Check a custom socket.

ls -l /tmp/tmux-$(id -u)/ /tmp/pair 2>/dev/null

Did the server reboot?

uptime -s

Attach, detaching others.

tmux attach -d -t migrate

For screen.

screen -ls; screen -d -r NAME

17. Lab 1: Survive a disconnect

Why do we need this?

Start a long job in tmux, detach, log out, log back in and reattach to see it still running.

What is it?

A full hands-on lab. Run every step on a test Linux machine (an EC2 instance, a VM, or WSL).

How to do it (step by step)

Start a session.

tmux new -s lab

Output:

[lab] 0:bash*

Run a long counter.

for i in $(seq 1 600); do echo tick $i; sleep 1; done

Output:

tick 1
tick 2

Detach and exit SSH.

Ctrl+b d ; exit

Output:

[detached (from session lab)]

Reconnect and list.

ssh ec2-user@SERVER; tmux ls

Output:

lab: 1 windows (created Sun Oct 25 15:00:00 2026)

Reattach and clean.

tmux attach -t lab   (watch ticks)   then Ctrl+c; exit

Output:

tick 143

18. Lab 2: Panes, copy mode, config and screen

Why do we need this?

Set up a config, split panes, copy an error from scrollback, then repeat the detach/attach with screen.

What is it?

A full hands-on lab. Run every step on a test Linux machine (an EC2 instance, a VM, or WSL).

How to do it (step by step)

Config.

printf 'set -g mouse on\nset -g history-limit 20000\nbind | split-window -h\n' > ~/.tmux.conf

Output:

(no output)

New session and split.

tmux new -s p2   then Ctrl+b |

Output:

(two panes side by side)

Make an error and find it.

ls /nope   then Ctrl+b [  ?nope Enter  Space ... Enter  Ctrl+b ]

Output:

ls: cannot access '/nope': No such file or directory

screen round trip.

screen -S s1   then Ctrl+a d ; screen -ls ; screen -r s1

Output:

	5120.s1	(Detached)

Clean up.

exit ; tmux kill-session -t p2

Output:

(no output)

Ravindra Bagale's Tip

Make it a habit: anything that takes more than five minutes on a server runs inside tmux. Name the session after the job (tmux new -s migrate), so when you come back after a network drop you just type tmux attach -t migrate.

19. Frequently asked questions

Q. tmux or screen?

tmux for new work (panes, scripting, active development). screen is fine where it is the only option.

Q. Does tmux survive a server reboot?

No. Sessions live in memory. Plugins like tmux-resurrect can restore layouts.

Q. tmux vs nohup?

nohup keeps one command alive but you cannot interact with it; tmux keeps a full interactive terminal.

Q. How do I scroll?

Ctrl+b [ then PgUp, or set -g mouse on.

Q. Can I change the prefix to Ctrl+a?

Yes: set -g prefix C-a; unbind C-b; bind C-a send-prefix.

Q. Should I run tmux on my laptop or on the server?

On the server, so work survives the SSH drop.

Q. How to close everything?

exit in each pane, or tmux kill-server.

Q. Can two people use one session?

Yes, attach to the same session; use -r for read-only.

20. Interview questions and answers

Beginner level

Q. Why use tmux?

Keep sessions alive after disconnects and split the terminal.

Q. Start a named session?

tmux new -s NAME.

Q. Detach?

Ctrl+b d.

Q. Reattach?

tmux attach -t NAME.

Mid level level

Q. Split panes?

Ctrl+b % left/right, Ctrl+b " top/bottom.

Q. Scroll back in tmux?

Copy mode Ctrl+b [ or mouse on.

Q. Run a job in a detached session?

tmux new -d -s NAME 'cmd'.

Q. screen equivalents?

screen -S, Ctrl+a d, screen -ls, screen -r.

Senior level

Q. tmux or a systemd service for a long job?

Interactive or one-off: tmux. Must restart, survive reboot or be monitored: systemd.

Q. How do you securely share a terminal with a contractor?

Separate socket with group perms, read-only attach, and audit; remove the socket after.

Q. Automate a dev workspace?

Script with has-session, new -d, split-window, send-keys, select-layout, or tools like tmuxinator.

Q. Why can nested tmux be a problem?

Prefix conflicts and confusion; use a different prefix on the inner one or switch-client.

Try at home

Write a script that builds a tmux session 'dev' with three panes: a shell, top, and tail -f of a log. Run it twice and make sure it does not create a duplicate.
Practice: start a session, detach, close the terminal, open a new one and reattach. Repeat with screen.

Practice Tasks

About this scenario

Nairobi Ride is a transport business in Nairobi. Wanjiru Kamau looks after its IT and cloud work. They count money in KES and run their AWS resources in the af-south-1 Region. In the tasks below you do real jobs for them using what this lesson teaches. All names, account IDs, IP addresses and numbers are made up for practice.

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