So, let's say for example, I need to run a tmux socket between two users that runs

echo foo

To make this run on a normal tmux, it'd be best to do tmux new -d -s Foo "echo foo"

However, when running tmux using -S, I can't seem to find a way to automatically run a command as the session starts. Let's say our path is /home/user/tmux

I'd run tmux -S /home/user/tmux, and then on another account tmux -S /home/user/tmux attach. However, this doesn't leave an opportunity to specify a starting command. Any way I could do this?



1 Answer 1


So one approach is to spawn a new window and then attach:

tmux -S /tmp/socket new-window -n vi /usr/bin/vi
tmux -S /tmp/socket attach

So the client can create a new window and then connect to it.

However, I suspect that a tmux session might not be doing what you want it to do.

The reason that attach has no command is because a session represents a view what is currently seen on the screen, which is shared between all connected clients. So attaching with a command is a little weird. All clients will view the same thing, and the new-window call will change the view for all attached clients.

If you want to share a collection of windows (e.g views of running programs), but have each client have a distinct view then you need to create sessions. You can use the -t argument to new-session to make a session that shares its windows with another session. Apparently you can't use -t together with a command for the new session, which is actually a valid use case, so you end up using the -d flag and then spawning the command. To make things even more irritating it would appear that new-window lacks a session argument, so you instead rely on the order that things are called!

tmux -S /tmp/socket new-session -s base  # run once

# For each client
tmux -S /tmp/socket new-session -t client-view -d 
tmux -S /tmp/socket new-window /usr/bin/vi
tmux -S /tmp/socket attach -t client-view

This is all a bit of kludge put I have managed to use this sort of approach effectively for a number of years. (Each of my terminal windows is a distinct view into a shared tmux session).

You might be interested in this script https://github.com/rainerborene/tmx/blob/master/tmx that wraps all of this up into a single shell script.

  • All the tmuxlib python library might be of tangential interest for you if you are trying to do complicated things with tmux.
    – Att Righ
    Feb 11, 2017 at 9:21

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