We've already learned how to use GNU Screen to manage multiple Terminal sessions. Today, we will see yet another well-known command-line utility named "Tmux", which is used to manage Terminal sessions. This guide explains what is Tmux and the Tmux command usage with examples in Linux.
1. What is Tmux?
Similar to GNU Screen, Tmux is also a Terminal multiplexer that allows us to create number of terminal sessions and run more than one programs or processes at the same time inside a single Terminal window.
Tmux is free, open source and cross-platform program that supports Linux, OpenBSD, FreeBSD, NetBSD and Mac OS X.
2. Install Tmux in Linux
Tmux is available in the official repositories of most Linux distributions.
To install Tmux in Alpine Linux, run:
$ sudo apk add tmux
On Arch Linux and its variants like EndeavourOS and Manjaro Linux, run the following command to install it.
$ sudo pacman -S tmux
On Debian, Ubuntu, Linux Mint, Pop_OS!:
$ sudo apt-get install tmux
On Fedora, RHEL, CentOS, AlmaLinux, Rocky Linux:
$ sudo dnf install tmux
$ sudo yum install tmux
$ sudo zypper install tmux
Well, we have just installed Tmux. Let us go ahead and see some examples on how to use Tmux.
3. Tmux command usage with examples
The default prefix shortcut to all commands in Tmux is
Ctrl+b. Just remember this keyboard shortcut when using Tmux.
Heads Up: The default prefix to all Screen commands is Ctrl+a.
3.1. Creating Tmux sessions
To create a new Tmux session and attach to it, run the following command from the Terminal:
$ tmux new
Once you are inside the Tmux session, you will see a green bar at the bottom as shown in the screenshot below.
It is very handy to verify whether you're inside a Tmux session or not.
3.2. Detaching from Tmux sessions
To detach from a current Tmux session, just press
d. You don't need to press this both Keyboard shortcut at a time. First press
"Ctrl+b" and then press
Once you're detached from a session, you will see an output something like below.
[detached (from session 0)]
3.3. Creating named sessions
If you use multiple sessions, you might get confused which programs are running on which sessions. In such cases, you can just create named sessions.
For example if you wanted to perform some activities related to web server in a session, just create the Tmux session with a custom name, for example "webserver" (or any name of your choice).
$ tmux new -s webserver
Here is the new named Tmux session.
As you can see in the above screenshot, the name of the Tmux session is webserver. This way you can easily identify which program is running on which session.
To detach, simply press
3.4. List Tmux sessions
To view the list of open Tmux sessions, run:
$ tmux ls
As you can see, I have two open Tmux sessions.
3.5. Creating detached sessions
Sometimes, you might want to simply create a session and don't want to attach to it automatically.
To create a new detached session named "ostechnix", run:
$ tmux new -s ostechnix -d
The above command will create a new Tmux session called "ostechnix", but won't attach to it.
You can verify if the session is created using
tmux ls command:
3.6. Attaching to Tmux sessions
You can attach to the last created session by running this command:
$ tmux attach
$ tmux a
If you want to attach to any specific named session, for example "ostechnix", run:
$ tmux attach -t ostechnix
$ tmux a -t ostechnix
3.7. Kill Tmux sessions
When you're done and no longer required a Tmux session, you can kill it at any time with command:
$ tmux kill-session -t ostechnix
To kill when attached, press
"y" to kill the session.
You can verify if the session is closed with
tmux ls command.
To Kill Tmux server along with all Tmux sessions, run:
$ tmux kill-server
Be careful! This will terminate all Tmux sessions even if there are any running jobs inside the sessions without any warning.
When there were no running Tmux sessions, you will see the following output:
$ tmux ls no server running on /tmp/tmux-1000/default
3.8. Split Tmux Session Windows
Tmux has an option to split a single Tmux session window into multiple smaller windows called Tmux panes.
This way we can run different programs on each pane and interact with all of them simultaneously.
Each pane can be resized, moved and closed without affecting the other panes. We can split a Tmux window either horizontally or vertically or both at once.
3.8.1. Split panes horizontally
To split a pane horizontally, press
" (single quotation mark).
Use the same key combination to split the panes further.
3.8.2. Split panes vertically
To split a pane vertically, press
3.8.3. Split panes horizontally and vertically
We can also split a pane horizontally and vertically at the same time. Take a look at the following screenshot.
First, I did a horizontal split by pressing
" and then split the lower pane vertically by pressing
As you see in the above screenshot, I am running three different programs on each pane.
3.8.4. Switch between panes
To switch between panes, press Ctrl+b and Arrow keys (Left, Right, Up, Down).
3.8.5. Send commands to all panes
In the previous example, we run three different commands on each pane. However, it is also possible to run send the same commands to all panes at once.
To do so, press
Ctrl+b and type the following command and hit
Now type any command on any pane. You will see that the same command is reflected on all panes.
3.8.6. Swap panes
To swap panes, press
3.8.7. Show pane numbers
q to show pane numbers.
3.8.9. Kill panes
To kill a pane, simply type
ENTER key. Alternatively, press
x. You will see a confirmation message. Just press
"y" to close the pane.
4. Zoom in and Zoom out Tmux panes
We can zoom Tmux panes to fit them into the full size of the current Terminal window for better text visibility and for viewing more of its contents.
It is useful when you need more space or focus on a specific task. After finishing that task, you can zoom out (unzoom) the Tmux pane back to its normal position. More details in the following link.
5. Autostart Tmux Sessions
It is always a good practice to run a long running process inside a Tmux session when working with remote systems via SSH.
Because, it prevents you from losing the control of the running process when the network connection suddenly drops.
One way to avoid this problem is to autostart Tmux sessions. For more details, refer the following link.
In this guide, we have discussed Tmux command usage with examples. At this stage, you will get a basic idea of Tmux command line utility and how to use Tmux to manage multiple Terminal sessions. For more details, refer man pages.
$ man tmux
Both GNU Screen and Tmux utilities can be very helpful when managing servers remotely via SSH. Learn Screen and Tmux commands thoroughly to manage your remote servers like a pro.