[Tmux Series 2] Install Tmux and Launch Your First Session

Tmux runs inside your terminal app and keeps shell work alive in the background. In this guide, you install it, create one session, leave that session running, and attach to it again.

The likely reader here is an English-speaking beginner on macOS who has already seen the basic idea of sessions, windows, and panes in Part 1 and now wants the first hands-on workflow.

What We'll Cover

• Install Tmux with Homebrew
• Create one session and run a simple command inside it
• Detach from that session and attach to it again
• Close the session cleanly when you are done

Before You Begin

You need a terminal on macOS and Homebrew installed. iTerm2 is fine, but Terminal.app works too.

• Terminal app: iTerm2, Terminal.app, or another macOS terminal
• Homebrew already installed
• About 10 minutes

If you skipped Part 1, keep this mental model in mind: a session is a workspace that stays alive even after you leave it.

Previous guide: Tmux Series Part 1: What is Tmux?

Step 1: Install Tmux

Start by confirming that Homebrew is available.

brew --version

If that command works, install Tmux.

brew install tmux

Typical install output looks something like this:

==> Downloading https://ghcr.io/v2/homebrew/core/tmux/...
==> Installing tmux
==> Pouring tmux--3.5...

The exact version and file path can vary. Apple Silicon Macs usually use /opt/homebrew, while Intel Macs usually use /usr/local.

Now confirm that tmux is available in your shell.

tmux -V

Expected result:

tmux 3.5

Your version number may differ. The important part is that the command succeeds.

Step 2: Create Your First Session

Create a session named mysession.

tmux new -s mysession

The name is just a label. Short names without spaces are easier to reuse later, such as work, study, or api_server.

When the session opens, your terminal still looks mostly normal, but Tmux adds a status bar at the bottom.

• [mysession] is the session name
• 0:bash* or 0:zsh* usually means window 0 is active
• Colors and exact layout depend on your terminal theme and shell

Run a simple command inside the session so you can recognize it later.

echo "Hello from tmux"
date

At this point, you are working inside Tmux even though it still feels like a normal shell.

Step 3: Detach From the Session

Detaching means leaving the Tmux view without stopping the work inside it.

Tmux commands usually start with a prefix key. The default prefix is Ctrl+b.

To detach:

1. Press Ctrl+b
2. Release both keys
3. Press d

It should feel like: Ctrl+b, release, then d.

Expected message:

[detached (from session mysession)]

After that message, you are back in your normal shell, but the session is still running in the background.

Step 4: Check Running Sessions

If you want to see which sessions currently exist, use tmux ls.

tmux ls

Typical output:

mysession: 1 windows (created Fri Mar 13 10:30:00 2026) [80x24]

The timestamp and terminal size may differ. The important part is seeing mysession in the list.

Step 5: Attach to the Session Again

Now reconnect to the session you just left.

tmux attach -t mysession

You should return to the same session with the same scrollback and command history still visible. That is the core Tmux workflow: leave a workspace, then come back to it later.

Step 6: Close the Session

If you are done with the session, close it from inside Tmux.

exit

That ends the shell running in the current window. If it is the only window in the session, the session closes and you return to your normal shell prompt.

If you are already detached and want to close the session from outside, use:

tmux kill-session -t mysession

Use kill-session only when you intentionally want to terminate that session from the outside.

Test the Full Workflow

Run this short practice loop once from start to finish.

# Create a session
tmux new -s practice

# Inside the session, run something easy to recognize
echo "Tmux is working"

# Detach with: Ctrl+b, release, then d

# Back in the normal shell, confirm the session still exists
tmux ls

# Reattach to it
tmux attach -t practice

# Exit from inside the session
exit

How to read the results:

• [detached ...] means you left the session but it is still running
• returning to your normal shell after exit means the session closed
• tmux ls helps when you forget a session name

Shortcut Recap

These are the only commands and shortcuts you need from this lesson.

Command or shortcut	What it does
tmux new -s name	Create a new session
Ctrl+b, then d	Detach from the current session
tmux ls	List running sessions
tmux attach -t name	Attach to a session
exit	Close the current shell inside Tmux

Common Mistakes

command not found: tmux

This usually means Tmux was not installed successfully or your shell cannot find it.

which tmux
brew install tmux

If needed, close and reopen the terminal after installation.

The detach shortcut does not work

The usual mistake is pressing Ctrl+b+d all at once.

Use this timing instead:

1. Press Ctrl+b
2. Release both keys
3. Press d

I forgot the session name

Use:

tmux ls

That shows the names of running sessions.

Session names with spaces are annoying

Quoted names can work, but they are harder to type later.

tmux new -s my_project
tmux attach -t my_project

Prefer letters, numbers, dashes, or underscores in session names.

I want to close a detached session

Use:

tmux kill-session -t mysession

If you want to terminate every running Tmux session, use tmux kill-server, but treat that as a last-resort cleanup command.

Practice Checklist

You are ready for the next post when you can do all of these without looking up every step.

• Install Tmux and confirm tmux -V works
• Create a session with tmux new -s name
• Detach with Ctrl+b, then d
• List sessions with tmux ls
• Reattach with tmux attach -t name
• Close the session with exit

Up Next

Once session creation, detach, and reattach feel natural, the next step is learning how to organize more than one task inside a session.

Tmux Series Part 3: Manage Sessions and Windows shows how to create multiple windows, switch between them, and keep different kinds of work organized.