# tmux and screen: keeping sessions alive over SSH

> tmux and screen keep a session running on the server when SSH drops: install steps, commands, and how the tools differ.

## Why use tmux and screen on a VDS

An SSH session drops when the connection is interrupted, a router reboots, or Wi-Fi disconnects. Every process running in that terminal receives a HUP signal and gets killed. If that process is `apt upgrade`, a kernel build, or a long database backup, the work is lost halfway through. **tmux** and **screen** solve this problem: they start a separate terminal session on the server that keeps running independently of the SSH connection. Disconnect, and the session keeps working. Reconnect, and you see the same screen with the same commands still running.

Both tools solve the same task but are built differently. Let's cover installation, basic commands, and how the tools differ.

## Installing tmux and screen

Both packages are available in the standard repositories of most distributions.

```
apt update
apt install -y tmux screen
```

For CentOS, Rocky Linux, and AlmaLinux:

```
dnf install -y tmux screen
```

Check the version with `tmux -V` and `screen --version`. For heavy tasks like migrating a database or building a package by hand, use these tools right after your [first SSH connection to the server](https://www.zevshost.net/en/kb/podklyuchenie-vds-ssh/), before starting the work.

## Basic tmux commands

tmux works with sessions, windows, and panes. A session can be named, which is convenient when you run several of them.

| Command | Action |
| --- | --- |
| `tmux new -s backup` | create a session named backup |
| `tmux ls` | list active sessions |
| `tmux attach -t backup` | attach to the backup session |
| `Ctrl+b d` | detach from the session |
| `Ctrl+b %` | split the window into panes vertically |
| `Ctrl+b "` | split the window horizontally |
| `tmux kill-session -t backup` | terminate the session |

The key combination starts with the `Ctrl+b` prefix, followed by a separate command key. This is what sets tmux apart from screen, where the prefix is `Ctrl+a`.

## Basic screen commands

screen predates tmux and is built more simply: one window equals one terminal, with no built-in pane splitting in the base version.

```
screen -S backup
screen -ls
screen -r backup
```

Detach from a session with `Ctrl+a d`, create a new window inside a session with `Ctrl+a c`, and switch between windows with `Ctrl+a n` (next) and `Ctrl+a p` (previous). Sometimes, after a dropped connection, a session stays in the "Attached" state, and reconnecting with `screen -r` returns an error. Run `screen -d -r backup` instead, which forcibly detaches the old connection.

## How tmux differs from screen

The difference goes beyond keyboard shortcuts.

- tmux can split a window into panes without extra packages; screen needs a module or a newer build for that.
- tmux supports a configuration file at `~/.tmux.conf` with flexible status bar and color scheme settings.
- screen runs on almost any Unix server without installation — it is often already present by default.
- tmux is developed more actively and usually restores its layout faster after an SSH disconnect.

For everyday work on a VDS, most administrators choose tmux for its panes and convenient configuration. screen remains a good option for minimal systems where you don't want extra packages installed.

## What to do after an SSH disconnect

If the connection drops on its own, not through `detach`, the tmux or screen session stays running in the background, and its processes keep going. Once the connection is back, simply reconnect over SSH and run `tmux attach` or `screen -r`. To avoid mixing up sessions, give them clear names right away, for example `tmux new -s deploy` instead of an unnamed session with a number.

For long background tasks with no interactive output, a real daemon managed by systemd fits better — for recurring jobs, see [creating a unit file for an auto-starting service](https://www.zevshost.net/en/kb/systemd-service-sozdat/) or [setting up the cron scheduler](https://www.zevshost.net/en/kb/cron-nastroika-linux/). tmux and screen are meant for interactive work: migrations, package installs, and real-time diagnostics.

## Summary: what to remember

- tmux and screen keep a terminal session running on the server when the SSH connection drops.
- Install with `apt install -y tmux screen` or `dnf install -y tmux screen`.
- In tmux the prefix is `Ctrl+b`; in screen it is `Ctrl+a`.
- Name sessions when creating them: `tmux new -s name`, `screen -S name`.
- Use systemd or cron for background tasks with no interaction, not tmux.

---

Source: https://www.zevshost.net/en/kb/tmux-screen-sessii/