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Using tmux

In this lesson, we'll learn how to use tmux to run a long running command.

Refresher

We'll use some concepts here that was learned in the previous lesson. You can take a quick look at them to refresh them:

tmux is a terminal multiplexer, which allows you to create and persist "shell sessions" on the server. This is helpful if you have to run a long-running command and don't want the process to be killed if your SSH connection is interuppted for any reason. This is also helpful if you have more than 1 person logging in to your server and you together need to work on the same session.

tmux allows you to attach multiple shells to the same terminal session. That means you can open a tmux window, split it into multiple parts (panes) and run different commands on each of them.

Our task for this lesson is to run a command nano week1/hello.txt. This command prints the message on the terminal but takes 60 seconds to complete.

Let's create a new session with:

tmux

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You'll be logged into your current user account. tmux is controlled using what is called as Modifier Key (Mod). The default hotkey for that is Ctrl+b. This combination will be referred to as mod from now onwards.

Running Commands

Let's run our command nano week1/hello.txt. You'll notice the editor is opened right now.

$ nano week1/hello.txt

Let's deattach from this session and return to our normal prompt. To do that, you'll need to use mod d. Once you do that, you'll be returned to the prompt from where you started the tmux session.

Deattach a session

mod d

List sessions

$ tmux ls
0: 1 windows (created Tue Dec 14 18:19:10 2021)

Attaching sessions

$ tmux a

Congrats! You completed the task for this lesson. We used tmux to run a long-running command and learnt how to attach/detach sessions.

Additional Shortcuts

Panes

  • mod %: To split a window vertically.
  • mod ": To split a window horizontally.
  • mod [: To add a scrollbar to the current pane.

You can move around the panes with mod + Right/Left/Up/Down arrow keys.

Windows

  • mod c: Create a new window.
  • mod p: Switch to previous window index.
  • mod n: Switch to next window index.

You can explore some handy cheatsheets like https://tmuxcheatsheet.com/ and https://devhints.io/tmux for more commands.