Advanced

Run as a Service

We're going to define a service to automatically run the Call Attendant on the Raspberry Pi at start up. Our simple service will run the callattendant.py script and if by any means is aborted it is going to be restarted automatically.

Create the Service

Step 1. Create the Unit File

The service definition unit file must be on the /lib/systemd/system folder. Our service is going to be called "callattendant.service".

But first, we must identify the path to the callattendant command. Use the which command to locate the callattendant script. Note the path, we'll use it later in the unit file.

which callattendant
/home/pi/.local/bin/callattendant

Now create the unit file using the nano editor:

sudo nano /lib/systemd/system/callattendant.service

Copy the following text into the callattendant.service unit file; edit the paths as necessary for your system using path identified earlier. You can use Ctl-Shift-V or Right-Click > Paste to paste this text into the nano editor.

[Unit]
Description=Call Attendant
After=multi-user.target

[Service]
Type=simple
ExecStart=/home/pi/.local/bin/callattendant --config app.cfg
Environment="PYTHONUNBUFFERED='True'"
WorkingDirectory=/home/pi/.callattendant
User=pi
Restart=on-abort

[Install]
WantedBy=multi-user.target

You can check more on service's options in the next wiki: https://wiki.archlinux.org/index.php/systemd.

Step 2. Activate the Service

Now that we have our service we need to activate it:

# Change the permissions on the service file to read/write
sudo chmod 644 /lib/systemd/system/callattendant.service

# Reload the unit files
sudo systemctl daemon-reload

# Enable the service...
sudo systemctl enable callattendant.service

# And now run the service
sudo systemctl start callattendant.service

Service Tasks

For every change that we do on the /lib/systemd/system folder we need to execute a daemon-reload (third line of previous code). Execute the following commands as needed to check the status, start and stop the service, or check the logs.

# Reload the unit file(s)
sudo systemctl daemon-reload

Start service

# Use the supplied command script
start-callattendant

# or use the system command
sudo systemctl start callattendant.service

Stop service

# Use the supplied command script
stop-callattendant

# or use the system command
sudo systemctl stop callattendant.service

Check/Monitor service's log

# Use the supplied command script
monitor-callattendant

# or use the system command
sudo journalctl -f -u callattendant.service

Check status

sudo systemctl status callattendant.service

REFERENCES

• https://wiki.archlinux.org/index.php/systemd
• https://stackoverflow.com/questions/37211115/how-to-enable-a-virtualenv-in-a-systemd-service-unit
• http://www.diegoacuna.me/how-to-run-a-script-as-a-service-in-raspberry-pi-raspbian-jessie/
• https://www.digitalocean.com/community/tutorials/understanding-systemd-units-and-unit-files
• https://coreos.com/os/docs/latest/getting-started-with-systemd.html

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Record Audio Files

You can record your own audio wav files for playback to your callers.

See: (https://iotbytes.wordpress.com/play-audio-file-on-phone-line-with-raspberry-pi/)