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I'm using tmux from a while and I'm very happy with it. Since I need it most of the time, I made it my default shell (in guake, to be precise).

This is nice and I'm perfectly fine with this.

But from time to time, I need to exit tmux and having a clean shell, but since I'm defaulted with tmux, terminating the session will result in another tmux later.

So, my question is: is it possible to replace the tmux process with a given shell?

Something like exec which, of course, doesn't work, because it replacess the shell inside tmux and not tmux itself.

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  • Since you only made tmux default in quake you could always just fire up an xterm/gnome-terminal/Terminal and that'll use your system default shell (which you seem to indicate you haven't changed). Of, for that matter, even if you did change your system shell, using the -e option in xterm (similar in other terminal programs) you could specify the shell to run in the terminal. e.g.: xterm -e /bin/bash Commented Mar 7, 2013 at 16:01
  • Thanks, this is what I usually do when I'm on a local machine, but sometimes I need to do the same task on remote ones where tmux is my system default. Commented Mar 7, 2013 at 16:07
  • 1
    well, then.... after already logged into the remote machine I don't know of anyway to do this without X. You can use the same technique with ssh: "ssh you@remote /bin/bash" and it'll run bash rather than your default shell. Alas, this probably still doesn't solve your problem. Commented Mar 7, 2013 at 16:40
  • why not simply use tmux <prefix>d to detach the session? Usetmux list-sessions to go back in tmux. Commented Nov 16, 2019 at 22:35
  • @xaa besides being an almost 7 years old question, but as you can read, I said that tmux is the default shell, so detaching it would close the terminal. Commented Nov 28, 2019 at 20:47

3 Answers 3

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I don't think tmux can do that. It should be easy to patch if you know C programming.

One thing you could do is call tmux from a wrapper shell script, and let the script decide whether to exit or not. Send a signal to the wrapper to tell it to execute an interactive shell when tmux exits. Here's an untested proof-of-concept for the wrapper script:

export TMUX_PARENT_PID=$$
trap 'exec bash -i' USR1
tmux

In ~/.tmux.conf:

update-environment DISPLAY WINDOWID SSH_ASKPASS SSH_AUTH_SOCK SSH_AGENT_PID SSH_CONNECTION TMUX_PARENT_PID

From within tmux, to get a shell prompt after detaching:

TMUX_PARENT_PID=$(tmux show-environment | sed -n 's/^TMUX_PARENT_PID=//p')
kill -USR1 $TMUX_PARENT_PID
tmux detach-client
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  • Nice idea to catch a signal in a wrapper script. Commented Mar 8, 2013 at 12:02
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If tmux is running, environment variable TMUX would be set, thus by putting lines like this in your bashrc, tmux would still be your shell.

But if it's already running, bash or other shell would run normally, (don't use chsh to set your shell to tmux, that can be a problem)

if [[ ! -z ${TMUX} ]]; then
    // run tmux
    tmux "$@"
    exit 0
fi
// tmux is already running
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I know I'm a few years late to the party, but after reading through @Gilles 's answer, I spent an hour or two redesigning my .profile file to add a signaling mechanism, which I believe might better answer the original question (the one in the body, not the title):

# Start tmux:
if [ -n "$(type tmux 2> /dev/null)" ] && [ -z "$TMUX" ]; then
    # Configure a signal handler to allow the tmux session to toggle the exit flag:
    export EXIT_FLAG=1
    export TMUX_PARENT_PID=$$
    trap 'EXIT_FLAG=$(($EXIT_FLAG ^ 1))' USR1

    # Start tmux:
    tmux new-session -s "shell$$" "TMUX_PARENT_PID=$$ $SHELL -l"

    # Exit, assuming the exit flag has not been flipped:
    if [ "x$EXIT_FLAG" == "x1" ]; then
        exit
    fi

    # Otherwise, cleanup the environment:
    unset EXIT_FLAG
    unset TMUX_PARENT_PID
    unset TMUX
fi

With this in my .profile, all shells will start tmux by default, and will also exit with tmux. If I want the shell to stick around after I've exited out of tmux, I just have to run kill -s USR1 $TMUX_PARENT_ID before I run exit, and the shell won't exit.

Note that the kill ... command above actually toggles the EXIT_FLAG variable, so running kill ... twice in a row effectively cancels itself out.

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  • I'll note here that this approach has been causing strange behavior in my xTerm. I used to just run exec tmux, which worked perfectly, but it looks like starting tmux directly from your .profile like an cause it to behave oddly. Commented May 13, 2020 at 22:38

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