How can I make TMUX be active whenever I start a new shell session?

session, shell, terminal, tmux

Solution

warning this can now 'corrupt' (make it unable to open a terminal window - which is not good!) your Ubuntu logins. Use with extreme caution and make sure you have a second admin account on the computer that you can log into in case you have the same problems I did. See my other answer for more details and a different approach.

Given that warning, the simplest solution can be to append the `tmux` invocation to the end of your `.bashrc`, e.g.

alias g="grep"
alias ls="ls --color=auto"

# ...other stuff...

if [[ ! $TERM =~ screen ]]; then
    exec tmux
fi

Note that the `exec` means that the bash process which starts when you open the terminal is replaced by `tmux`, so `Ctrl-B D` (i.e. disconnect from tmux) actually closes the window, instead of returning to the original bash process, which is probably the behaviour you want?

Also, the `if` statement is required (it detects if the current bash window is in a tmux process already) otherwise each time you start tmux, the contained bash process will attempt to start its own tmux session, leading to an infinite number of nested tmuxen which can be, err, quite annoying (that said, it looks cool).

However, there is a very small risk this can make `bash` behave in a way that other programs don't expect, since running bash can possibly cause it to turn into a tmux process, so it might be better to modify how you start your terminal emulator.

I use a small executable shell script `~/bin/terminal` (with `~/bin` in `$PATH`, so it is found automatically) that looks a bit like:

#!/bin/sh
exec gnome-terminal -e tmux

(I don't use gnome-terminal, so you might have to remove the `exec`, I'm not sure.)

Now whenever you run the `terminal` scipt you have a terminal with tmux. You can add this to your menu/desktop/keyboard shortcuts to replace the default terminal.

(This approach also allows you to more easily customise other things about the terminal emulator later, if you ever desire.)

Problem

Original source