tmux new session won't start on my Ubuntu server 16.04.2

I have a freshly installed Ubuntu server 16.04.2 and tmux 2.1. When tmux isn't running (i.e when I'm in a regular session) I ran the following tmux heredocument which I use to download, install, use, and delete certain programs in a timeout in the background:

(
cat > /dev/shm/my_script.sh && 
chmod +x /dev/shm/my_script.sh && 
tmux new-session -d '/dev/shm/my_script.sh; rm /dev/shm/my_script.sh'
) <<-'EOF'
	# apt-get install utility
        sleep 5h
        # apt-get purge utility
EOF

In this new system, the heredocument fails to work - I run it and it seems to have been runned successfully but nothing changes in the system - No tmux session will start and no utility will be installed.

I would thank you dearly for your opinion on this.

[nicm]

Is the new install the same tmux version?

Yes, both remote machines are with tmux 2.1.

[nicm]

I guess something must be running tmux at startup, you should probably try to figure out what that is.

…

On 29 Apr 2017 10:03 pm, "Benqzq" ***@***.***> wrote: Yes, both environments (two different remote machines) are with tmux 2.1. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#900 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AASkc0XzbbqGXzyveyA5p1HaE-vB6zloks5r06WYgaJpZM4NMW3n> .

I made sure tmux won't start in reboot, and indeed it doesn't start wit the system. I am in a regular session and tmux ls brings:

no server running on /tmp/tmux-0/default

Yet, when I run the heredocument above on the new server, nothing happens. It's just doesn't work though the code is valid.

[nicm]

what if you do:

tmux new-session -d '/dev/shm/my_script.sh; rm /dev/shm/my_script.sh; sleep 1000'

In this case a session does created.

[nicm]

Right... and if you attach, do you see an error message from your script?

Indeed, that's all I see when I attach:

bash: /dev/shm/my_script.sh: No such file or directory
rm: cannot remove '/dev/shm/my_script.sh': No such file or directory

[nicm]

Apparently your script doesn't work then or it is running before /dev/shm is mounted.

…

On 29 Apr 2017 10:46 pm, "Benqzq" ***@***.***> wrote: Indeed, that's all I see when I attach: bash: /dev/shm/my_script.sh: No such file or directory rm: cannot remove '/dev/shm/my_script.sh': No such file or directory — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#900 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AASkc4O-71z_2y7fk-kwAHFEwLtYHnfTks5r06-YgaJpZM4NMW3n> .

I can swear the script is fine as I checked each command separately. What you say about executing it before /dev/shm is mounted, is interesting. Allow me to have your take on this for the last time, please, as I'm new to Linux: Is a situation when /dev/shm isn't mounted on bootstrap seems plausible to you? As far as I know this is not natural, and it might be part of a bigger problem.

[nicm]

So what happens if you don't use /dev/shm and write the script in /tmp or /root?

[nicm]

This does seem like something you could do more sensibly with at rather than tmux TBH.

It's not executed in /tmp or /root. I prefer not to use at...

I now notice the exact problem is this:

The script can be executed when I do cd /dev/shm but when I'm out of this mounted device, it won't be executed.

This behavior is new - I didn't experience it before. Can you please try explain it? It could help me much...

[nicm]

I don't know. Perhaps you should pick a way to do this that is easier for you to trouble shoot.

This the easiest way I know and the only one I wish to use. Sorry for not updating (planned to do so later today), but I've found why I didn't work and I also made a slight change to the script:
tmux new-session -d '/dev/shm/script.sh; rm /dev/shm/script.sh'

Should have been:

tmux new-session -d 'bash /dev/shm/script.sh; rm /dev/shm/script.sh'

But in any case my final version was basically as:

(
cat <<-'PMA' > /opt/script.sh
#!/bin/bash
cd /var/www/html
wget SOME_FILE
sleep 2h
tmux kill-session
PMA
chmod +x /opt/script.sh
tmux new-session -d 'bash /opt/script.sh'
tmux new-session -d 'rm /opt/script.sh'
)

For those who want to expand - Please read here.