Start tmux and execute a set of commands on boot

Question

I'm trying to find a way to have tmux start for a specific user on boot. The tmux session should run two Python scripts.

I think I could start Python as mentioned here, but I'd rather have it in a tmux session.

Is that possible and how could I accomplish that?

Answer 1

In my case, I have a user account just for the purpose of running one single script, so I provide a default tmux configuration in that user's home directory by creating a file ~/.tmux.conf

My ~/.tmux.conf file looks (roughly) like this:

new-session -d -s MYSESSIONNAME
set -g status off
new-window ~/my-startup-script.sh

my-startup-script.sh needs to have the +x permission set, obviously.

To start the ~/.tmux.conf tmux script, issue the command

tmux start-server

Answer 2

On a system where cron @reboot runs too early in the boot sequence, I run a shell script of the pattern

#!/bin/bash
source ~/.bash_profile
if tmux has-session -t auto-session > /dev/null 2>&1; then
    :
else
    tmux new-session -d -s auto-session -n foo bar
    tmux new-window -d -t auto-session
fi

regularly every few minutes via crontab

*/2 * * * * $HOME/path/to/start-user-auto-session.bash

Answer 3

I have tried the answers posted before me but it is cryptic to me. So I decided to figure out a simpler solution with less parameters.

I got a cheat sheet from the web. Here is a good example

Some commands that I use on daily basis are:

• create new TMUX session tmux new -s SESSIONNAME
• to list session tmux ls
• to attach existing session to the terminal tmux a -t SESSIONNAME
• to kill the session tmux kill-session -t SESSIONNAME
• send key to an existing session tmux send-keys -t SESSIONNAME "cd /pathname/"

Here is an example of how one can interact with an existing session.

# create two new sessions SES1 and SES2 and detach them.(-d -s is important)
tmux new-session -d -s SES1
tmux new-session -d -s SES2

# let us send some commands to the other session (Python for example)
tmux send-keys -t SES1 "ipython3" C-m
tmux send-keys -t SES1 "from numpy import zeros" C-m
tmux send-keys -t SES1 "a = zeros((10,10))" C-m

Now If you open SES1 in the new terminal window you will see ipython running and two commands executed.

$ ipython3
Python 3.8.5 (default, Jul 28 2020, 12:59:40) 
Type 'copyright', 'credits' or 'license' for more information
IPython 7.13.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: from numpy import zeros                 

In [2]: a = zeros((10,10))                      

In [3]:  

Method 1: This is my favorite and I have been extensively using it.

create file nano ~/.tmux.conf

content of the file

#TMUX start-up script
new-session -d -s SES3
set -g status off #NOTE: this will disable the status bar(green text in the bottom. Personally, I like it there.

send-keys -t SES3 "ipython3" C-m
send-keys -t SES3 "from numpy import zeros" C-m
send-keys -t SES3 "a = zeros((10,10))" C-m

Method 2: The next step would be to create a script and run it on start-up. See this for example

create a file tmux_startup in /etc/init.d/.

sudo nano /etc/init.d/tmux_startup

file example

#!/bin/bash
# chkconfig: 2345 20 80
# description: Description comes here.... tmux script runs on startup.

tmux new-session -d -s SES1
tmux new-session -d -s SES2

tmux send-keys -t SES1 "ipython3" C-m
tmux send-keys -t SES1 "from numpy import zeros" C-m
tmux send-keys -t SES1 "a = zeros((10,10))" C-m

When you boot your system you should see the sessions you created.

$ tmux ls

Answer 4

This post has been extremely valuable! We took some of the solutions here and combined them into an easy to use bash function which can be reused:

# Parameters: session_name working_directory command_to_run
ensure_tmux_session() {
    # echo $1 $2 $3
    # https://unix.stackexchange.com/questions/443569/start-tmux-and-execute-a-set-of-commands-on-boot
    if tmux has-session -t $1 > /dev/null 2>&1; then
        :
    else
        tmux new-session -d -s $1 
        tmux send-keys -t $1 "cd $2" C-m
        tmux send-keys -t $1 "$3" C-m
    fi
}

Example usage:

ensure_tmux_session session_name "~/my_dir" "./my_script param1 param2"

Answer 5

Over at another question I've been asked to add an answer here as well, containing one aspect of my answer there. So this is an attempt to do so and expand upon it.

So far, none of the answers here provide a way to make tmux inside of crontab work without requiring an additional script. My technique will work on any system which supports Cron's @reboot extension. This should be true for most modern distributions, but your mileage may vary and it may not be available out of the box.

It's just a one-liner. Here's an example for crontab which will have top waiting for you once you connect (tmux attach -t my_session) to my_session sometime after boot:

@reboot tmux new-session -d -s my_session 'top'

If you like, you can get more fancy. The original example showed a more complex last argument to tmux new-session which will not only start the command and show its output inside of the session's first (and only) window, but also log the output to a file at the same time. Using Mosquitto as an example here:

@reboot tmux new-session -d -s my_session "bash -c 'mosquitto -c /etc/mosquitto.conf -p 1883 -v 2>&1 | tee /tmp/mosquitto_nodaemon.log'"

May the source be with you!

(Mods, if you feel like this answer should be worked into another and then deleted, please feel free to do so.)