Difference between revisions of "Systemd service file"

Latest revision as of 11:24, 17 April 2024

If i want a service daemon to log if my server is online every minute. The following procedure could be used:

My service

#!/bin/bash
# Filename: /usr/local/sbin/mysserver-online.sh
# Owner: root:root
# Permissions: 755

IP="192.168.1.72"
LOGFILE="/tmp/myserver.log"
export LOGFILE

# Example: Bash catches(trap) exit signal and runs cleanup function (Not necessary) 
#          $LOGFILE used in trap routine - needs to be exported
cleanup() {
        echo "$(date): Cleaning up" | tee -a $LOGFILE
}
trap 'cleanup' EXIT



echo "$(date): Starting service" | tee -a $LOGFILE

while :
do
        if ping -c 1 $IP > /dev/null 2>&1
        then
                echo "$(date): online" >> $LOGFILE
        else
                echo "$(date): OFFLINE" >> $LOGFILE
        fi
        sleep 60
done

My service-file

# Filename: /lib/systemd/system/mysserver-onlined.service
# Owner: root:root
# Permissions: 644
[Unit]
Description=Test if my server is online
After=network.target

[Service]
ExecStart=/usr/local/sbin/mysserver-online.sh
Type=simple
Restart=always


[Install]
WantedBy=default.target

Enabling the service

Copy files to destination

Make sure your service and your service-file are in the right destination.

sudo cp myserver-online.sh /usr/local/sbin
sudo chown root:root /usr/local/sbin/myserver-online.sh
sudo chmod 755 /usr/local/sbin/myserver-online.sh

sudo cp myserver-onlined.service /lib/systemd/system
sudo chown root:root /lib/systemd/system/myserver-onlined.service
sudo chmod 644 /lib/systemd/system/myserver-onlined.service

Reload system file

systemd reloads and hopefully finds your new service-file

sudo systemctl daemon-reload

Verify files

systemd-analyze checks the service-file for errors. (Correct errors if any - remember to reload system files)

sudo systemd-analyze verify myserver-onlined.service

Enable service-file

Enabling the service file makes it a part of systemd If it is a service and should be running all the time - do shutdown -r now and check with systemctl status myserver-onlined that it is running

 sudo systemctl enable myserver-onlined.service

Need to know commands

# Check the service status
sudo systemctl status myserver-onlined

# Start the service manually
sudo systemctl start myserver-onlined

# Stop the service manually
sudo systemctl stop myserver-onlined

# Restart the service manually
sudo systemctl restart myserver-onlined

# If you make changes to the service file - reload
sudo systemctl daemon-reload

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