I created two files, ecu.py and /etc/systemd/system/boo.service
ecu.py
#!/bin/env
print("hello world")
/etc/systemd/system/boo.service
[Unit]
Description=example systemd service unit file.
[Service]
Type=simple
User=user
StandardOutput=tty
TTYPath=/dev/pts/1
WorkingDirectory=/home/user
ExecStart=/usr/bin/python3 ecu.py
[Install]
WantedBy=multi-user.target
In my system, my login is user and my tty is pts/1
sudo systemctl start boo.service pops on my terminal hello world
maybe this can help you.
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I have tried various combinations with your suggestion. Initially I started out by pasting exactly what you wrote to my boo.service. Initially the only change I made is to my home directory which is pi not user I then tried changing tty to pi. No effect on my system.
I do not understand the implications of TTYPath=/dev/pts/1 but based on the below I tried 0, 1, ptmx. None produced any output. Not even a new terminal was opened.
pi@bananapi:~$ ls -al /dev/pts/
total 0
drwxr-xr-x 2 root root 0 Jan 1 1970 .
drwxr-xr-x 15 root root 4940 Jul 11 15:28 ..
crw--w---- 1 pi tty 136, 0 Jul 11 15:29 0
crw--w---- 1 pi tty 136, 1 Jul 11 15:30 1
c--------- 1 root root 5, 2 Jan 1 1970 ptmx
pi@bananapi:~$
user pi is logged on, ps will show the terminal associated with it. The idea is to tell systemd to output to that tty. In my case:
user@cw:~$ ps
PID TTY TIME CMD
2003339 pts/1 00:00:00 bash
2003353 pts/1 00:00:00 ps
user@cw:~$
user@cw:~$ ll /dev/pts/1
crw--w---- 1 user tty 136, 1 Jul 11 07:00 /dev/pts/1
user@cw:~$
show ps when logged on as pi@bananapi This will tell you the tty. Verify that tty exists in /dev with correct perms.
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From this link, systemd.exec
StandardOutput=
Controls where file descriptor 1 (stdout) of the executed processes is connected to. Takes one of inherit, null, tty, journal, kmsg, journal+console, kmsg+console, file:path, append:path, truncate:path, socket or fd:name.
TTYPath=
Sets the terminal device node to use if standard input, output, or error are connected to a TTY (see above). Defaults to /dev/console.
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I will investigate the above later. In the meantime here is the response to the command!!!
sudo systemctl status boo.service
● boo.service - example systemd service unit file.
Loaded: loaded (/etc/systemd/system/boo.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Thu 2024-07-11 17:40:45 CEST; 1min 18s ago
Process: 2447 ExecStart=/bin/python3 /home/pi/ECU.py (code=exited, status=209/STDOUT)
Main PID: 2447 (code=exited, status=209/STDOUT)
Jul 11 17:40:45 bananapi systemd[1]: Started example systemd service unit file..
Jul 11 17:40:45 bananapi systemd[2447]: boo.service: Failed to set up standard output: No such file or directory
Jul 11 17:40:45 bananapi systemd[2447]: boo.service: Failed at step STDOUT spawning /bin/python3: No such file or directory
Jul 11 17:40:45 bananapi systemd[1]: boo.service: Main process exited, code=exited, status=209/STDOUT
Jul 11 17:40:45 bananapi systemd[1]: boo.service: Failed with result 'exit-code'.
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Based on a suggestion from another forum the below worked fine for me:
[Service]
StandardOutput=tty
TTYPath=/dev/tty9
In order to see the effect of the print statement one just has to do Cntl+Alt+F9.
To return to the GUI , I had to use Cntl+Alt+F7. This may be different for other GUI's
This basically means that the earlier suggestion by @pavlos_kairis of using tty1 would have worked too as all I needed to do was press Cntl+Alt+F1.
Thanks for all the help.
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