systemd service - hello world

In previous posts, I found a workaround for the iwlwifi crashing driver. In this post, I wrote small script to detect the crash and apply the workaround. Also, I installed systemd service to run the script on boot so i don’t have to.

Starting with the script. It’s basically while(1) to monitor the crash

found=0
while [ $found -eq 0 ]
do
    rm -f /tmp/d.log
    dmesg > /tmp/d.log
    if tail -n 5 /tmp/d.log |grep -q "Failed to wake NIC for hcmd" ; then
        echo "Fixing iwlwifi"
        echo "1" > /sys/bus/pci/devices/0000:03:00.0/remove
        echo "1" > /sys/bus/pci/rescan
    fi

    sleep 5
done

The service itself is very simple, just ExecStart to call the script.

[Unit]
Description=Fix iwlwifi crash

[Service]
ExecStart=/bin/bash /home/user/fix-iwlwifi-crash.bash

[Install]
WantedBy=multi-user.target

To install the service, I just need to create /etc/systemd/system/fixiwlwifi.service and i am good to go.

sudo touch /etc/systemd/system/fixiwlwifi.service

The last thing is starting the service and enabling it.

sudo systemctl start fixiwlwifi # to start the serveice
sudo systemctl enable fixiwlwifi # to enable at boot time