tmux

Definition

Terminal Multiplexer. A software application that allows multiple terminal sessions to be accessed simultaneously in a single window, and keeps terminal sessions running in the background even if you disconnect.

Explain Like I'm New

Tabs and windows for your terminal, plus a safety net. If your Wi-Fi drops while you are running a 3-hour script, `tmux` keeps the script running safely on the server. When Wi-Fi comes back, you reconnect and the script is right where you left it.

Real World Example

An engineer opens `tmux`. They split the screen in half. On the left, they run the Node server. On the right, they watch the log files using `tail -f`. They close their laptop, go home, open it back up, SSH in, type `tmux attach`, and both screens are still running perfectly.

Common Use Cases

•Protecting long-running scripts from network drops
•Managing complex workspaces via SSH

Interview Questions

basic

If you start a command inside `tmux` and then accidentally close your terminal window, does the command die?

intermediate

What is the 'Prefix Key' in tmux?

Flash Cards

Question

Does the command die?

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Answer

No! That is the entire point of `tmux`. The session 'detaches' and continues running in the background infinitely on the server until you re-attach to it or manually kill it.

Question

What is the Prefix Key?

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Answer

Because `tmux` runs *inside* your terminal, it needs to know when a keyboard shortcut is meant for the app you are running, and when it is meant for `tmux` itself. By default, pressing `Ctrl+B` tells tmux 'The very next key I press is an instruction for you' (like splitting the screen).