Add instructions to install as cron job

README.md

@@ -22,3 +22,44 @@ The tool reads the following environment variables:
 | -------- | --------------------------------------------------------------------------------- | ------------- |
 | LOGIN    | DynHost login. The tool will exit if this environment variable is not defined.    |               |
 | PASSWORD | DynHost password. The tool will exit if this environment variable is not defined. |               |
+
+## Installation
+
+### cron job
+
+Run the following commands to download the tool:
+
+```bash
+sudo wget https://github.com/Tomy2e/ovh-dynhost-updater/releases/latest/download/ovh-dynhost-updater-linux-amd64 -O /usr/local/bin/ovh-dynhost-updater
+sudo chmod +x /usr/local/bin/ovh-dynhost-updater
+```
+
+Update the `CHANGEME` values then run the following commands to create the file
+that contains your DynHost credentials:
+
+```bash
+sudo bash -c "cat >> /usr/local/etc/ovh-dynhost-updater-creds" << EOL
+export LOGIN=CHANGEME
+export PASSWORD=CHANGEME
+EOL
+sudo chmod 0700 /usr/local/etc/ovh-dynhost-updater-creds
+```
+
+Open the crontab file:
+
+```bash
+sudo crontab -e
+```
+
+Append the following line to your crontab file, update the `CHANGEME` values,
+then save:
+
+```bash
+*/10 * * * * (. /usr/local/etc/ovh-dynhost-updater-creds && /usr/local/bin/ovh-dynhost-updater --hostname=CHANGEME) 2>&1 | logger -t ovh-dynhost-updater
+```
+
+The tool will run every ten minutes, run the following command to see the logs:
+
+```bash
+grep 'ovh-dynhost-updater' /var/log/syslog
+```