Jessie Startup Scripts

From Technologic Systems Manuals

A systemd service can be created to start up headless applications. Create a file in /etc/systemd/system/yourapp.service

[Unit]
Description=Run an application on startup

[Service]
Type=simple
ExecStart=/usr/local/bin/your_app_or_script

[Install]
WantedBy=multi-user.target

If networking is a dependency add "After=network.target" in the Unit section. Once you have this file in place add it to startup with:

# Start the app on startup, but will not start it now
systemctl enable yourapp.service

# Start the app now, but doesn't change auto startup
systemctl start yourapp.service
Note: See the systemd documentation for in depth documentation on services.

To start an application on bootup with X11 instead change the x-session-manager. By default the system starts xfce:

root@ts:~# ls -lah /usr/bin/x-session-manager 
lrwxrwxrwx 1 root root 35 May 26  2015 /usr/bin/x-session-manager -> /etc/alternatives/x-session-manager
root@ts:~# ls -lah /etc/alternatives/x-session-manager
lrwxrwxrwx 1 root root 19 May 26  2015 /etc/alternatives/x-session-manager -> /usr/bin/startxfce4

The x-session can be modified to only start specified processes. Create the file /usr/bin/mini-x-session with these contents:

#!/bin/bash
matchbox-window-manager -use_titlebar no &

exec xfce4-terminal

You may need to "apt-get install matchbox-window-manager." first. This is a tiny window manager which also has a few flags that simplify embedded use. Now enable this session manager and restart slim to restart x11 and show it now.

chmod a+x /usr/bin/mini-x-session
rm /etc/alternatives/x-session-manager
ln -s /usr/bin/mini-x-session /etc/alternatives/x-session-manager
service slim restart

If the x-session-manager process ever closes x11 will restart. The exec command allows a new process to take over the existing PID. In the above example xfce4-terminal takes over the PID of x-session-manager. If the terminal is closed with commands like exit the slim/x11 processes will restart.